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tps5352

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Note: See new Post #49 for further thoughts on how to test for the effects of wheel/tire sizes on range.​
*****​

Talking Points
  • Target audience: Readers new to Rivian and/or electric vehicles in general. (But input from experienced Rivian drivers is welcomed.)
  • Premise: Rivian SUVs and pickups are great. But can range be improved (by wheel/tire selection)?
  • Justification: Why need/want more range? We discuss the (many) factors that increase, and (relatively few) factors that decrease, the rate-of-loss of battery energy (leading to range reduction). Savvy buyers tend to want the most range possible.
  • Focus within the article:
    • The most range-efficient Rivian models.
    • An introductory look at wheels and tires.
    • Four inherent objectives.
    • Rivian OEM wheels and factory-recommended tire sizes.
    • How to choose among many wheel/tire options, while avoiding undesirable issues?
    • What pathways are available to change wheels/tires if increased range is an objective?
Introduction

I'm an armchair proponent of greater electric-car range.² (For some of us, it's all about “range, range, range.”) I have also become something of a closet (As in hopefully “out of” in 2025?) fan-boy for the full-sized Rivian SUV. The result? How to get the maximum (R1S) range. I acknowledge that there are at least two points of view on range--for example, see one here and another here--both worthy of consideration. For more on this, see Appendix A ("Why Want More Range?).

Rivian R1T R1S Range Against the Machine¹ - Rivian OEM Wheels, Tires, and Range Considered Some Areas Where Rage is not just a Luxury

- Source -
Figure 1. For a recreational-vehicle,
there are some locations where
range is not a luxury, it’s a necessity.​

Experienced Rivian and BEV drivers—especially those putting in lots of on- and off-road miles--may know all this. So this article is primarily intended for us newbies (to Rivian and/or to electric vehicles). Though my focus is on the big Rivian SUV and pickup, general lessons may apply to other (future) vehicles, as well.

First Step – Choosing the Most Range-Efficient Model

Some considerations:
  • number of motors
  • battery size
  • wheel size
  • tire size, tread design, and efficiency
First, take advantage of Rivian's online “Build” and “Shop” interactive features to provide maximum range estimates for various wheel/tire combinations and on new and inventory vehicles.

Rivian R1T R1S Range Against the Machine¹ - Rivian OEM Wheels, Tires, and Range Considered How to Choose

- Source Video -
Figure 2. Lots of videos to consider on YouTube.​

At the moment³ the stock R1S and R1T vehicles with the greatest range (EPA estimated 410 and 420 miles, respectively) are the Adventure (or “Performance”) Dual Max versions. These most-range-efficient models have two (not 3 or 4) motors, and Rivian’s largest (141 kWh) Max battery. So far so good. What can be done using wheels and tires?

Second Step, Wheels and Tires

I think I’ve heard Martin Brundle (1980s-90s Formula 1 driver and, now, preeminent F1 commentator) on more than one occasion refer to tire science as “magic.” And judging by the number of postings, tires are frequently on the minds of many Rivian drivers. Here are two comprehensive online lists of OEM and aftermarket replacement tires that may be satisfactory for Rivian trucks and SUVs:
And a visual list of the Gen 1 and some Gen 2 Rivian OEM wheels can be found here:
How might this information help us increase range?

The Effects of Changing Wheel and Tire Sizes

What people may loosely call a "wheel" often means both the central (metal) wheel itself and the outer, inflated, rubber tire. A "wheel set" can be both the (four) wheels and the tires together (plus other parts like the TPMS air pressure sensors, aero-wheel-covers, lug-nuts, etc.). Since wheels and tires are obviously circular, they both have (center to edge) radius, (edge to edge) diameter, (distance around the outer edge) circumference, and width measurements. In addition, tires critically also have tread width and sidewall height. The total height of a wheel + tire together is the tire's diameter (= sidewall height + wheel diameter + sidewall height). Since for any circle radius (1/2 the diameter), diameter, and circumference are all strictly interrelated, to know one is to know all three. Tire tread width, and tire sidewall height, and wheel diameter can vary, however, even if tire radius, diameter, and circumference are held constant.

Considering all the different kinds of vehicles over the years, it is in no way an exaggeration to say that there are an incredibly huge number of different sizes of wheels and especially sizes of tires. Even for one particular vehicle there may be tens or hundreds of different wheel/tire products that will fit (possibly requiring modification). Choosing the best tires in particular can be a major chore (for help, see here, here, or here). And there are many legitimate factors that can influence the choice of tires, including:
  • price
  • appearance
  • weight
  • sidewall height
  • tread width
  • tire pressure
  • performance
  • wear and durability
  • tread design and rubber composition
  • usefulness on pavement and in mud, sand, and snow
  • intended climate and season
  • et cetera, et cetera...
This article focuses on the narrow idea of simply increasing range--the number of miles that can be driven from one charging session to another. Range is related to multiple factors including the efficiency of the tire, rolling resistance, tread design, tire pressure, and many others.

The Effect of Wheel and Tire Sizes on Range

Normally, wheels with larger diameters partnered with tires with correspondingly smaller sidewall heights (lower-profile tires) tend to reduce range. (See also, Appendix B.)

Rivian R1T R1S Range Against the Machine¹ - Rivian OEM Wheels, Tires, and Range Considered Decreasing Range

Figure 3. Range generally decreases with larger
wheels and lower-profile tires.​

But Rivian’s current choice of wheel-sets for the 2025 Dual Max vehicles for example, and their range estimates, seem to defy this supposition.

  • 20” wheels with all-terrain tires – 370/370 miles
  • 22” wheels with performance tires – 410/420 miles
The simple explanation may be that in this case the range comparison is probably skewed in favor of the larger wheels (despite their lower-profile tires). Why? Probably because deeper, more aggressive tread designs (e.g., on all-terrain tires) also tend to reduce on-pavement range. This was (partially) demonstrated in this video. But the “experimental design” in that video was not ideal, as different vehicles with different tire tread designs were compared. As some pointed out, a more impartial test would have compared just one pertinent variable (say tire diameter) at a time, holding all other variables (e.g., tire brand-model, and especially the specific test vehicle) constant (e.g., see here). But clearly the expense, effort, and time necessary to perform a series of more "scientific" experiments is beyond the abilities of average drivers.

So this post will (correctly, I think) assume that (a) decreasing the size of wheels (within reason) while maintaining overall tire diameter (by increasing sidewall height) and (b) replacing deeper off-road and all-terrain tire tread designs with more shallow, pavement-friendly (e.g., “all-season,” “performance,” “touring,” “highway,” etc.) tread versions may tend to help increase range.

By the way, readers might have noticed that Rivian does offer the option of a 20-inch so-called "All-Season" wheel set to ostensibly improve range. But to my knowledge this is only for the (least expensive) R1T and R1S Adventure Dual Standard models.

Sticking With Rivian Stock (OEM) Wheels and Approved Tire Sizes

For this preliminary analysis, I think that considering only Rivian OEM wheels, tire sizes, and tire capacities is wise. This helps guarantee proper fit and safety (and by limiting the number of wheel/tire products makes the analysis more manageable). In addition, a focus has been on wheel-tire combinations that do not require that speedometer software be reprogrammed. (For more on that topic, see here and Appendix C.) If you have the time, peruse this long thread: Scorpion AS+ tire swap (from 20" Scorpion AT) - WOW big difference. In it you can see some of the imagined advantages and real disadvantages of straying outside of the lines (as far as tire size). For better or worse my thinking echoes that of this entry.

To repeat myself, this post is intended as a preliminary start for new Rivian drivers/buyers and not as an extensive review of every possible individual wheel and tire combination. Aftermarket wheels are not considered, for example. (Yet I’m sure that there are many excellent choices available which achieve proper fit, appearance, strength, durability, light-weight, and other desirable characteristics.)

Here is a quick look at first (Gen 1) and second (Gen 2) generations of wheel-tire combinations offered by Rivian for R1S and R1T (click to enlarge):

Rivian R1T R1S Range Against the Machine¹ - Rivian OEM Wheels, Tires, and Range Considered GEN 1

Figure 4. Rivian OEM Gen 1 (10/21 -5/24) wheels and tires.


Rivian R1T R1S Range Against the Machine¹ - Rivian OEM Wheels, Tires, and Range Considered GEN 2

Figure 5. Rivian OEM Gen 2 (6/24 -->) wheels and tires.​

Summary of Analysis Objectives

The following preliminary wheel-tire substitution analysis includes at least four built-in, inherent objectives:
  1. To consider possible alternative wheel-tire combinations that may increase maximum range, primarily by reducing wheel size, retaining tire diameter, and avoiding off-road, mud & snow, and aggressive all-terrain tire tread designs.
  2. To bypass if possible the need to reprogram speedometer software (see Appendix C).
  3. To utilize Rivian Gen 1 & Gen 2 factory wheels and appropriately matched tire sizes.
  4. To follow safety guidelines and (specifically) consider tires with Load Indices of at least 116.
Note: Objective 2 can be achieved with the help of an online tire-size calculator. (For more on them, see Appendix D).

Note: For safety reasons, any results that follow must be treated as theory and speculation for discussion purposes. Definitive conclusions would require verification by trusted professional tire experts, proper and safe empirical testing, and/or valid real-world results by experienced drivers in order to substantiate. Increased range is not guaranteed.


Table 1. Some Possible Tire Options for Increasing T1T/R1S Range (Part 1)
(Rivian Generation 1 Vehicles)

Factory Wheels/TiresAlternative 1Alternative 2
Wheel Diameter:
20
20
21
Tire Brand & Model:​
Pirelli Scorpion AT+​
Tire Category:​
Light Truck, All-Terrain​
Touring, All-Season​
Tire Size:​
275/65R20​
- same -​
Tread Width:​
10.83​
- same -​
Sidewall Height:​
7.04​
- same -​
Tire Diameter:​
34.08​
- same -​
Tire Circumference:​
107.07​
- same -​
True Speed (@65 mph):​
65​
65​
Wheel Diameter:
21
21
20
Tire Brand & Model:​
Pirelli Scorpion Verde
Michelin Defender LTX M/S2
Tire Category:​
All-Season, Touring​
All-Season, Highway​
All-Season, Touring​
Tire Size:​
275/55R21​
- same -​
275/60R20​
Tread Width:​
10.83​
- same -​
- same -​
Sidewall Height:​
5.95​
- same -​
6.5​
Total Tire Diameter:​
32.9​
- same -​
33​
Tire Circumference:​
103.36​
- same -​
103.67​
True Speed @65mph:​
65​
65​
65.2​
Wheel Diameter:
22
20
21
Tire Brand & Model:​
Pirelli Scorpion Zero​
Tire Category:​
All-Season, Performance​
All-Season, Touring​
All-Season, Touring​
Tire Size:​
275/50R22​
275/60R20​
275/55R21​
Tread Width:​
10.83​
- same -​
- same -​
Sidewall Height:​
5.41​
6.5​
5.95​
Total Tire Height:​
32.82​
33​
32.9​
Tire Circumference:​
103.11​
103.67​
103.36​
True Speed @65mph:​
65​
65.4​
65.2​


Table 2. Some Possible Tire Options for Increasing T1T/R1S Range (Part 2)
(Rivian Generation 2 Vehicles from June 2024 onward)​

Note: As of March 2025, it appears that Dual Large, Dual Max, and Tri Max vehicles with the AT Package still receive 34" (Pirelli) tires. (Dual Standard vehicles, only, continue to receive 33" Goodyear Wrangler Territory AT tires, if the all-season wheel-set option is selected.)

|Factory Wheels/TiresAlternative 1Alternative 2
Wheel Diameter:
20
20
20
Tire Brand & Model:​
Goodyear Wrangler Territory AT¹⁰
¹¹
Tire Category:​
All-Season​
All-Season, Touring​
|
Tire Size:​
275/60R20​
- same -​
|
Tread Width:​
10.83​
- same -​
|
Sidewall Height:​
6.5​
- same -​
|
Total Tire Diameter:​
33​
- same -​
|
Tire Circumference:​
103.67​
- same -​
|
True Speed @65mph:​
65​
65​
|
Wheel Diameter:
20
20
21
Tire Brand & Model:​
Pirelli Scorpion AT+​
Tire Category:​
Light Truck, All-Terrain​
Touring, All-Season​
Tire Size:​
275/65R20​
- same -​
Tread Width:​
10.83​
- same -​
Sidewall Height:​
7.04​
- same -​
Total Tire Diameter:​
34.08​
- same -​
Tire Circumference:​
107.07​
- same -​
True Speed @65mph:​
65​
65​
Wheel Diameter:
22
20
21
Tire Brand & Model:​
Pirelli Scorpion AT+ or
Pirelli Scorpion MS​
Tire Category:​
All-Season, Performance​
All Season​
All Season​
Tire Size:​
275/50R22​
275/60R20​
275/55R21​
Tread Width:​
10.83​
- same -​
- same -​
Sidewall Height:​
5.41​
6.5​
5.95​
Total Tire Diameter:​
32.82​
33​
32.9​
Tire Circumference:​
103.11​
103.67​
103.36​
True Speed @65mph:​
65​
65.4​
65.2​


Table 3. Some Substantive Reasons to Change Wheel Size

Start With:Change to 20" Wheel:Change to 21" Wheel:Change to 22" Wheel:
20" Wheel
- na* -​
?​
better performance,
appearance​
21" Wheel
greater selection of tires​
- na -​
?​
22" Wheel
better range, comfort, noise​
?​
- na -​
_____
* na = "not applicable"


Table 4. Some Optional Pathways To Possibly-Increased Range

Starting TiresNew Wheels Required?Possible New TiresRe-calibration Needed?
1 - 275/60R20 (33" diam.) AT​
no​
275/60R20 (33) AS
no​
2 - 275/65R20 (34) AT​
no​
275/65R20 (34) AS
no​
3 - 275/55R21 (33) Road​
yes
275/60R20 (33) AS
no​
4 - 275/50R22 (33)​
yes
275/60R20 (33) AS
no​
Additional Pathways
(added expense)
5 - 275/60R20 (33) AT​
yes
275/65R20 (34) AS​
yes
6 - 275/55R21 (33) Road​
yes
275/65R20 (34) AS​
yes
7 - 275/50R22 (33)​
yes
275/65R20 (34) AS​
yes

Comments

Gen 1 and Gen 2 Wheels (Figures 4 and 5)
  • The information in the Figures is from the Rivian website (https://rivian.com/) and other online sources.

  • In Figures 4 and 5 (and in the tables within each figure), note the use of color to indicate shared measurements.

  • Rivian Gen 1 wheel and OEM tire combinations result in either 33-inch (“33s”) or 34-inch (“34s”) diameter (i.e., ~103” or ~107” circumference) tires. If (a) replacing wheels/tires and (b) trying to avoid the inconvenience of reprogramming speedometer software, try to replace tires with others of the same diameter. (Note that wheel diameter can be changed without necessarily changing the overall tire diameter. See Figure 9.)
The Four Analysis Objectives
(Listed just below Figure 5.)​
  • Consider the four objectives as preliminary guidelines. That said, wheel/tire safety is important when you are dealing with a large, heavy, fast, quick, powerful, and expensive vehicle.
Tables 1 and 2
  • This analysis does not specifically recommend what wheel and tire combinations a driver (seeking greater range) should use. That is probably not practicable, as there are far too many unknowable factors that could play a part in making such a decision. Instead, it is up to the interested reader to:
    • First, establish the starting wheel and tire sizes.
    • Second, examine the best options for alternative wheel and tire sizes, for example that would not require speedometer re-calibration.
      |
  • There are a number of resources available to select new tires:
    • Use one of the online tire-guides cited in this article, for example here.
    • Using online tire information, build a computer spreadsheet. (This is initially labor intensive, but eventually provides the easiest and most convenient way to manipulate tire information.)
    • Use a favorite tire shop website.
    • Visit and talk to tire experts in person. (But use appropriate caution. Tire salesmen are there to sell tires. It is ultimately your responsibility to get the best product.)
      |
  • In some cases the number of tire options within a specific wheel-size and tire-size category is severely limited or entirely absent. This may be due to an owner's desire to avoid speedometer re-calibration or just to a lack of all-season-like tires that satisfy Rivian weight/safety requirements.

  • As others have commented on, it appears that the 21-inch Rivian wheel has led to somewhat of an “orphan product” situation (i.e., an item that, for various reasons, is not considered lucrative and hence not receiving proper development and promotion by [in this case] tire manufacturers).
Tables 3 and 4
  • Table 3 is fairly self-explanatory. Experienced drivers may have many other reasons for switching wheel and tire sizes.

  • Table 4 is intended to alert readers as to what is in store for various wheel/tire changes--e.g., the added expense of wheel and tire purchase, plus the possible cost of speedometer software reprogramming.
Some Preliminary Conclusions
  • Unless you enjoy losing money and/or like storing wheels and tires for long periods in your garage, always try to buy a new/used vehicle with the wheels and tires you want. That said, sometimes a deal is too good and you just have to buy a car with the wrong wheels/tires.

  • If you plan to eventually search for aftermarket tires to try to improve range, you have a few options (see Table 4). You may want to think about if and how you will dispose of the original tires and (if necessary) wheels (e.g., for storage or sale). Also, which initial wheel and tire size makes the most sense for you and your plans? Another consideration, can you avoid speedometer software re-calibration?

  • It is my opinion--and it is just an opinion--that (all else being equal) if maximum range is desirable it would be best to start with a 20-inch wheel and 34-inch tire set, as this provides the largest number of alternative all-season-like higher-profile tire products that (with research or experimentation) may be found to provide improved range. Twenty-inch wheels and 33-inch tires may serve, as well; albeit with fewer available replacement tire choices at this time.

  • Readers who make it this far will see that despite all the words (above), the story is not yet complete. It's only just begun. See Post #49 for the next step--how to test the theory that maximum range might be achieved with 20-inch wheels and 34-inch highway tires.

****************************************************

APPENDICES

A. More About Range

How to Think About Range as a Number?

There are at least three valid ways to think about range numerically:
  1. As an official estimate of (maximum) range that a car can be driven when fully charged, often based on U.S. EPA determinations. EPA or other official estimates, provided by auto-makers and other online sources, are usually determined under strict laboratory or field conditions, and are often higher than what an average driver can expect to achieve in real-world conditions (see Range Consideration Number 2).

  2. As a real-world (average) range that drivers can achieve while driving in actual situations. Usually, these values will be significantly less than maxim range estimates, for a number of reasons. For example, drivers are often urged by car-makers not to charge to 100 percent or drive to zero-percent state of charge. Furthermore, real-world conditions are usually not ideal; weather conditions, age of the car and its batteries, driving style, payload, tire wear, the road surface, traffic, and many other factors all can reduce range.

  3. As a rate of range decline. In between charging sessions range is normally declining (even while parked). The rate of decline, however, can both increase and decrease. The average rate of this energy loss clearly impacts range. Just as an ICE car has range based on the volume of gasoline it can carry and the varying rate of gas used while driving/idling, a BEV has range based on the storage capacity of its high-voltage battery array and the varying rate of energy expenditure. As gas-mileage in an ICE car is affected by various conditions and driving behavior, there are a number of factors that affect the rate of battery-energy decline. The base-rate of decline during a single trip is probably determined initially by relatively-unchanging factors (like weight of the car, aerodynamics, and other engineering characteristics). But the rate of decline is also constantly varying with speed, headwind, incline, use of accessories, addition and subtraction of payload, and so forth. In general, the greater the average rate of decline the lower the ultimate range will be between charging sessions.
Why Want More Range?

It is a sad fact of life that there are very many (often fun, exciting, comfortable, interesting, convenient, or cheeky) things that hasten the decrease in electric-car range, while there are relatively few (and at that, usually boring, sedate, cautious, and dull) things that slow that inevitable decline.¹²

An electric car’s range budget is a constantly changing balance-sheet of energy stored onboard and rates of energy-expended while driving and parked. Maximum onboard energy storage is primarily determined by the size/volume/efficiency of the car’s high-voltage battery array. The ever-changing rate of energy expended is a pretty much a continuous (though varying) thing, even when the car is supposedly shut off; with many obvious and some unseen activities endlessly draining energy from the batteries.

Naturally, a primary expenditure of energy is the use of electrons stored in the battery to power the electric drive motor(s) while you are tooling down the road. That is unavoidable. Some electric cars weigh less, are more aerodynamic, or are otherwise more efficient. But they all use up energy that is translated into movement (and lost through friction and heat). But what additional factors sap energy and decrease maximum range?

Some of the things that further decrease range (in no particular order) include:
  • Driving aggressively (e.g., jack-rabbit starts and rapid speeds).
  • Towing.
  • Off-road and winter conditions like traveling through mud, dirt, sand, and snow.
  • Carrying a large payload (of people and things).
  • Driving uphill and on twisty roads.
  • Weather, including head-winds, precipitation, and low/high ambient temperatures.
  • Power-sapping accessories (including especially energy-hungry gadgets like on-board refrigerators).
  • Running the A/C and heaters.
  • The so-called "vampire drain" from various optional settings and modes in onboard software (like Tesla’s notorious Sentry Mode; does that also include Gear Guard?) and from unseen/unknown car components.
  • Certain wheel and tire designs and sizes—e.g., high-performance and off-road tires, and some non-stock sizes and designs.
  • Tire pressures not at recommended levels.
  • Auto-makers’ recommendations that cars with certain battery types not normally charge past 80% capacity (to increase long-term battery life).
  • The natural aging of batteries and other parts.
  • The sad fact that many estimated maximum range values are from the start seemingly inflated, calculated under absolutely perfect and difficult-to-duplicate laboratory conditions, or otherwise in no way indicative of true real-world conditions. (Not all car brands are equally guilty of this.)
Clearly, doing the opposite of these things (where possible) will help reduce the rate of energy loss and thereby maintain range. Actions that may help sustain maximum range in between charging sessions include:
  • Driving smoothly and sedately at recommended speed limits.
  • Sticking to smooth, well-maintained paved roads.
  • Relying on effective/efficient regenerative braking.
  • Managing long-term battery life (e.g., by not charging past 80%).
  • Using factory wheels and tires maintained at recommended pressures.
  • Performing routine maintenance.
  • Using internal climate-control devices sparingly.
But I ask you, is life worth living under these conditions? Frankly, I do not see Rivian (and other brands) adopting these bullet points to highlight their otherwise exciting PR campaigns.

Somewhat like the value of most new cars as you leave the dealership, once you drive away from a charger the level of energy is definitely going to decline; sometimes slowly and sometimes quickly, but decline regardless and not increase until you can reconnect again to a charging source. (Someday, all electric cars may have to be Aptera-like and include effective solar panels to help maintain the state of charge. But the technology is not there yet for most BEVs, which are too heavy, too non-aerodynamic, or living in non-amenable areas, weather-wise.)

So what is a range-concerned electric-car enthusiast to do? Once you select the brand-model you prefer (based on various factors), I recommend that you get the specific car/truck with the greatest inherent range possible (that you can afford). This will send the message to car-makers that customers value range. And until electric car charging attains the three re-fueling objectives established some time ago by ICE cars—generous driving range, an abundance of easily-accessible fueling stations, and quick and easy re-fueling—critics will continue to have ammunition to disparage the (otherwise clearly important) switch from petroleum to electricity.

B. Lower Profile Tires

Often seen on high-performance sports cars, the modern incarnation of relatively lower-profile tire designs normally provide better handling and performance, and have become increasingly popular with customers desiring performance (or the appearance of performance) in many types and price-levels of cars (Reference). But lower-profile tires may provide such benefits at a cost—e.g., reduced ride comfort, increased likelihood of tire and wheel damage, more road noise, faster tire wear, and reduced mileage are not uncommon. Some wonder why Rivian promotes 22-inch wheel-tire sets at the expense of a 20-inch wheel-(34") road tire option that truly maximizes range and gives better ride comfort?¹³ Whatever the reason, it should not stop drivers desiring greater range from reasonable experimentation.

Rivian R1T R1S Range Against the Machine¹ - Rivian OEM Wheels, Tires, and Range Considered Tire Size Comparison - 4

Figure 6. Side-by-side comparison of
lower- and higher-profile tires.​

C. Speedometers and Tires

Accurate speedometer readings are an obviously desirable and important safety feature. Since about 1910 dashboard speedometers have determined the rate of vehicular speed by various mechanical and/or electronic means. Regardless of the mechanism, the size (specifically circumference) of drive tires can often influence speedometer and other readings, so speedometers are routinely calibrated/programmed to take into account the size of factory-provided, stock (OEM) tires.

Although a very common practice, for obvious safety and liability reasons most auto-makers discourage drivers from changing the size of OEM, factory-supplied wheels and tires. But manufacturers (like Rivian) sometimes offer their own optional wheel-tire sets for a particular vehicle that may differ enough in size to possibly require speedometer re-calibration when switching from one optional wheel/tire to another.

In these days of increasingly computerized cars, some onboard software has begun to allow drivers to switch from among factory-optional-only wheel-sets. (Tesla software is one such example.) I do not believe that Rivian onboard software provides that feature just yet. Instead, drivers must currently pay (~$150) to have their car software updated in order to return the speedometer to accuracy after installing certain new tire sizes. This analysis intends to avoid that cost and inconvenience.

D. Tire-Size Calculators

I don’t know about you, but I initially found tire sizes rather perplexing. For example, “275/65R20 LT.” What the heck does it mean?

Rivian R1T R1S Range Against the Machine¹ - Rivian OEM Wheels, Tires, and Range Considered Tire Size Codes

- Source -
Figure 7. Some tire sidewall codes.​

I suspect that when new tires are needed the majority of consumers simply walk into a discount tire store and put their trust totally in the employees there. And in most instances maybe that is OK.

But when you have specific needs, a particularly valuable or specialized car, you really want the best outcome, and you don’t want to be pushed into buying this week’s overstocked tire model, just as with any other important (and expensive) decision it pays to do your homework ahead of time. Fortunately there is something called the Internet…

The numbers and codes embossed on the sides of tire can be interpreted with the help of many websites (for example here). They have to do with features such as the:
  • various tire-size dimensions
  • intended weight and class of vehicle
  • inflation pressure
  • load and speed indices
  • special needs (e.g., rain, mud, and snow)
and so forth.

In this case we are particularly interested in the wheel diameter, and in the diameter and sidewall height of tires to be considered. As you may recall, diameter translates directly into circumference by using the formula C = 2πr (circumference equals two times “pi” times the radius). By the way, “π” is the Greek symbol for that elusive number “pi” and is (approximately) 3.14. Pi is the ratio of any circle’s circumference to its diameter.

But is there an easier way to compare tires that does not involve high school Algebra, creating spreadsheets, or breaking out the old Texas Instruments calculator? Yes.

Rivian R1T R1S Range Against the Machine¹ - Rivian OEM Wheels, Tires, and Range Considered Texas Instruments Calculator - 1

Figure 8. Remember this?
Texas Instruments
hand-held calculator.​

Many online sites provide convenient online tire-size calculators. Here are just a few:
The most convenient online calculators allow you to compare starting and replacement tire specifications, provide side-by-side figure comparisons, and include original and new speed information (so you can tell if speedometer re-calibration would be necessary).

By entering the starting tire size (say 275/50R22--the current Rivian 22-inch performance wheel-set size) and a possible alternative (say 275/60R20--a 20” wheel and tire), you can pretty quickly compare diameter, sidewall height, circumference, and better yet, even true speed variations, thereby determining if speedometer re-calibration are necessary.

Rivian R1T R1S Range Against the Machine¹ - Rivian OEM Wheels, Tires, and Range Considered Example of Inch-Up - 1

- Source -
Figure 9. "Inching-Up" is not strictly possible using
Rivian OEM wheels only. But this figure illustrates
in general how tire diameter can stay the same
while wheel diameter changers significantly (e.g.,
from 15" up to 18" in one-inch increments). The
trick is changing tire sidewall height ("profile").​

Using an online tire-size calculator and a good list of Rivian-compatible tires will help point you in the right direction the next time tires need changing—especially if you feel the need for experimentation, with improved range as a goal for example.

****************************************************

Footnotes

In the Body of the Text

¹ Alternate titles: “The Lone Ranger,” Open Range,” “Chasing Range,” “Range Finder,” “Free Range,”
“At Close Range,” “Full of Range,” “Road Range,” etc., etc. :)

² My theory in a nutshell:
  • Local/regional air quality, human health, and other factors will significantly improve with a shift from internal combustion engine (ICE) to battery-electric (BEV) vehicles.
  • A timely switch to BEVs should therefore be encouraged.
  • Although BEVs allow a new, novel convenience—easily charging overnight, at home--many drivers are unable to charge at their residence and/or must sometimes travel long distances requiring the use of a manufacturer’s or third-party charging stations.
  • As we all remember, ICE cars traditionally enjoyed generous range, plus extremely accessible and quick fueling.
  • To further encourage uncertain consumers to consider the switch from ICE to BEVs, we need those three critical BEV charging factors—range, fueling accessibility, and time to refuel—to continue to improve.
³ As of November 2024 specifications are apparently not yet fully known for the 2025 (4-motor)
Ascend Quad Max.​

That’s pretty good for a big, heavy, and not particularly streamlined SUV. It should provide
a practical real-life range in the mid- to upper-300s, perhaps.​

In Tables

According to online tire guides (for example) at least 19 different All-Season and Touring
tires are available in the 275/65R20 size with adequate Load Capacity and other characteristics. Prices vary from $181 to $418 per tire, tread depth from 12/32" to 16/32". Interested readers are advised to check out descriptions and specifications (plus videos) on pertinent tire-store and tire-manufacturer's websites. Links to these are available on the tire guide websites (here and here), In particular, pay attention to tread design/depth and what reviewers say. I, myself, am initially interested in what may be a possible "Goldilocks" option (not too soft, not too hard, etc.)--the Continental TerrainContact H/T tire.​
There appear to be no 21" tires that meet (load) requirements and maintain diameter/
circumference. Plus, in this case it probably makes little sense to increase wheel size.​

As others have noted, there are really only two available tire brand-models in this 275/55R21,
21" wheel-diameter size. Will the Michelin provide greater range? Unknown.​

There are, maybe, five 275/60R20 tires with the right characteristics that are considered "all-
season" or "touring" tires. All have Load Indices of 116, which is acceptable. Prices range from $212 to $290; tread depth from 10/32" to 13/32". Manufacturers include Michelin Goodyear, and Yokahama. Whether it is worth the time and money to replace 21" wheels and tires with one of these 20" sets is unknown. (Money might be saved by purchasing used 20" Rivian wheels.) In comparison, in some cases range might conceivably be improved by replacing 22" wheels with 20" wheels and 275/60R20 highway or touring tires.​

Only Michelin & Pirelli all-season tires with proper characteristics are available in this 275/55R21
size. (See also Footnote 7.)​

¹⁰ This wheel-tire option is available from Rivian only on the Dual Standard SUV and pickup truck
versions. A greater number of tire options appears to be available in the 275/65R20 size.​

¹¹ Certain tires in 275/65R20 and 275/55R20 sizes are available, might conceivably provide better
range, but would require speedometer adjustment.​

In Appendices

¹² With the one exception of buying your car! That is one of the few things you can do that can
be both (a) fun and (b) able to increase range. Though arguably less exciting, another thing you can do may be replacing wheels and tires (hence the point of this post).​

¹³ The answer may be that Rivian has just accepted things as they are and is just giving
customers what they want. (Plenty of other manufacturers do that—i.e., sacrifice ride comfort and mileage to provide automotive performance and fashion.)​

****************************************************

Additional References

Some Rivian-Forums Posts & Threads
Other Websites
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Electrified Outdoors

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great write up! Its an excellent discussion to have. I have found that Rivian seems to be the most efficient of the current EV truck offerings.

I would add that efficiency is not tied to the battery pack selection. For example, the dual standard and the dual max will have essentially the same efficiency (miles per kWh) if all else is the same (e.g. wheels/tires, etc.).

The single largest factor I have found with most all EVs is the wheel and tire combo. Because EVs carry significantly less energy than a gasoline vehicle they are more significantly affected by small changes in efficiency. For example, our 2021 Honda Pilot has an 18 gallon gas tank and gets about 22-24 mpg on average. The Rivian R1 (gen1 large page with 131 kWh usable) carries the equivalent of about 4.5 gallons of gas and gets the equivalent of 70 mpg.

Lastly, the Rivian charges pretty fast. I suspect in many cases the standard pack will be enough for most folks. Those who want more performance and fewer charging stops on long road trips might opt for the Large or Max packs. If you plan to tow, definately go with max pack as towing will, at minimum cut the range in half.

For those new to EVs I think range anxiety causes them to think they need much more range than they actually will use 95% of the time.

What I have been suggesting to most folks struggling with battery pack selection or just to see what longer road trips might be like in their Rivian is to go on to https://abetterrouteplanner.com and plug in some of the destinations they typically or plan to visit to see what the range and road trips might be like.

Lastly, the range wheels on Gen2 have very expensive tires ($550 each last time I checked). Do the math to figure out if you actually need all that range and if it is really saving you money vs other wheel and tire options. This is a huge consideration for Rivian as most only get about 30k or less out of a set due to the weight and high torque of these vehicles.
 

zefram47

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It's not all about range and suggesting people buy as much range (battery) as they can afford is a good way for folks to spend more than necessary. The average driver in the USA does something like 40 miles per day. The vast majority of people don't do much road tripping either. The only real reasons to get as much range as possible is being off-grid a lot in remote areas OR someone who expects to tow long distance frequently. In almost every other situation it's just not necessary. Short of those two use cases, I'd take a faster charging EV over one with twice the range. I say this being someone that both goes off-road and has towed a car 1000 miles in a difficult charging environment. I've also done over 6000 miles worth of road trips at this point including Denver to Chicago in the middle of winter with single-digit temps.

I also started my EV journey in 2019 with a Chevy Spark EV that had 80 miles of range on a good day and more like 50 miles in the middle of winter. For $7.5k it was a great introduction to EVs and what I actually needed. That car handled 90% or more of my daily driving needs and I've yet to find a situation where my Quad+Large Rivian on all-terrains can't do what's needed...though again, I'd love to have the 180 kWh battery that was teased for the original Max pack while towing.
 

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This post is probably better as a book. Can I get this on my Kindle?

P.S. Don't overthink it. You might get an extra 10miles with one set of tires over another but then the wind changes direction or you do 1 mph faster and it's all irrelevant. Reminds me of friend who was big into road cycling and would wax lyrical about weight saving with some fancy carbon fibre pedals he paid loads for. Told him that taking a decent sh!t before going out would save that weight (and cost). As would simply losing some body fat.
 

docwhiz

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You didn't mention the largest factor in range which is driving speed. Energy use rises exponentially with greater speed.

(Newbies tend to be obsessed with range anxiety. After a while you'll figure it out.)
 

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Nice job. I'm also a HUGE proponent of more range. Between the fact that lower daily charging, colder weather, and impact of everything else on the higher efficiency of electric motors, all meaning 300mi *rated* range is often in the low-200s or even high-100s in reality, but people mindlessly parroting the "300 is all you need" line, it doesn't get enough attention that a 400-500mi vehicle is so much more useful in numerous situations over a 300mi one.

Do you have any data on running with a tonneau cover on the R1T? Given the impact, I'm kind of surprised that it's optional equipment.
 

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Great write up. I am fine with the range I have but my driving doesn't really require higher range. 23-QM-22", at most get 300 miles. Our drives through the Northeast has plenty of chargers so we don't run into issues.
 

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Great write up OP! Bravo!!

If you purchased the vehicle with the OEM tires and you intend to keep them till they're worn out, pretty much only a limited number things you can do to increase range:
1) Slow down, driving in excess of 65MPH kills range, period.
2) Control your impulse to gun it off the line at every traffic signal. It's difficult, but you can do it!
3) Keep tires inflated to vehicle manufacturer specs shown on the door pillar sticker.
4) Judicial use of climate control system, especially during winter in gen 1 vehicles without the heat pump. That resistive heating element just sucks up power.
 
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lgyee4

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Good work applying broad bandwidth to this.
I see you live in California and as a fellow resident, I got over range anxiety early by going on trips to San Diego, Portland, Lake Tahoe and other places easily. The R1T's 300+ miles easily is tremendous. Our infrastructure is pretty good and becoming more robust. No need to over think this, just get out there!
 

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iansriv

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OP-great post. Very well thought out. I admire your well thought out ideas on increasing efficiency. I needed an SUV and the R1S suited my needs best. Unfortunately, like most SUVs it has the aerodynamics of a brick and so I did not expect good range efficiency. It does have better a drag coeffiency (.297) than most SUVs. I believe the MB EQS (.20) and Lucid Air (.197) are very good. These differences lead me to not bother about any incremental improvements. Cheers.
 

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I think the EPA "Where the Energy Goes" site deserves a reference somewhere in this writeup.
https://www.fueleconomy.gov/feg/atv-ev.shtml

I like how it shows a stark comparison of inefficiencies between ICE, hybrid, and EV's.
 

carsly

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Very thoughtful approach to answering your own question.

However I'd posit that most potential buyers don't need more than 250 miles of range. Sure, 300 sounds nicer, but practically makes no difference in the majority of user scenarios.

Alternative questions are around:
1 - more robust and reliable charging infrastructure
2 - faster charging when on road trips (car and charger limitations)
3 - creative approaches to (1) and (2)

Supercapacitors, solid state batteries and even flow batteries can potentially address some of the time to charge concerns which then alleviate range concerns when the combination of 1 + 2 approaches that of gasoline vehicles. Tesla has written and published the book on (1) which is fantastic. I think (3) still needs some exploration, but the rub is these scenarios apply to very few people.

Until we have more weight-efficient and faster-charging onboard electrical storage the answer won't be taking 7,000 lbs SUV and making them 8,000 or even 9,000 lbs or we'd all be driving Hummer EV's - and practically no one is.

Summing up, range isn't the game for most people. It's about optimizing charging - location availability and speed. No need to carry more batteries than necessary, that's wasteful.
 

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It's not all about range and suggesting people buy as much range (battery) as they can afford is a good way for folks to spend more than necessary. The average driver in the USA does something like 40 miles per day...
All valid. Some (lucky) people are not prone to RA (range anxiety). (I didn't mention that I drove a Honda Clarity hydrogen fuel cell car for four years [my first electric car], and that experience probably made me more sensitive to RA than the average person :) ).

I laid out my arguments for more range in this post in another Forum. You're right that not everybody needs more range, and that most people probably don't need to be anxious. But after talking to friends and acquaintances who still drive ICE cars, I continue to think that as a country if we want to promote electric-car use, which I think we should, we need to make charging as much like (gasoline) re-fueling as possible (i.e., very quick and convenient) and give BEVs an average range similar to that for ICE cars, which I hope we will. But your points are well-taken.
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