Forged vs Cast Wheels? Weight/Strength/Longevity

BigE

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I had reached out to Rivian as to whether their wheels will be forged or cast. This is the response I got.

Thank you for waiting patiently while I researched your question further. Rivian has not announced details on our suppliers at this time, but all of Rivian's wheels are engineered for performance and adventure. The 20” wheel options on both the R1T and R1S are forged. The 21” and 22” wheel options are tilt cast and flow formed.

I hope that this helped! Please let us know if you have further questions.

Have an adventurous day,
Katy
8 a.m. to 8 p.m. CST - M-F
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cohall

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Glad to hear the 20's are forged, as that's what I configured the R1T with. From my understanding, forged wheels are superior in almost every way. Stronger, lighter, less prone cracking etc. The big downside is cost, as they are significantly more expensive to manufacture then cast/flow forming.

BTW, "Flow Forging/Forming" is really just a marketing term. They are cast wheels.
 

sevengroove

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Glad to hear the 20's are forged, as that's what I configured the R1T with. From my understanding, forged wheels are superior in almost every way. Stronger, lighter, less prone cracking etc. The big downside is cost, as they are significantly more expensive to manufacture then cast/flow forming.

BTW, "Flow Forging/Forming" is really just a marketing term. They are cast wheels.
I also came to a similar conclusion after reading up on the difference. What I still don't understand then is, how are the 21's still the configuration with the best range? Wouldn't the lower weight and rolling mass of the forged 20's make them better suited to delivering the best range, especially if paired with AS tires?
 
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BigE

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Glad to hear the 20's are forged, as that's what I configured the R1T with. From my understanding, forged wheels are superior in almost every way. Stronger, lighter, less prone cracking etc. The big downside is cost, as they are significantly more expensive to manufacture then cast/flow forming.

BTW, "Flow Forging/Forming" is really just a marketing term. They are cast wheels.
My hope was all sizes were forged. To pay a significant cost, say $3,500 for the dark 22" in cast, may just go with stock and then aftermarket?
 
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BigE

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I also came to a similar conclusion after reading up on the difference. What I still don't understand then is, how are the 21's still the configuration with the best range? Wouldn't the lower weight and rolling mass of the forged 20's make them better suited to delivering the best range, especially if paired with AS tires?
My guess is the 20" AT tire is very heavy.
 

cohall

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I also came to a similar conclusion after reading up on the difference. What I still don't understand then is, how are the 21's still the configuration with the best range? Wouldn't the lower weight and rolling mass of the forged 20's make them better suited to delivering the best range, especially if paired with AS tires?
Rolling resistance of the tire and weight of the tire both hurt the 20". You can also make cast wheels very light, but the lighter they are, the less material is used, the weaker they become. Rivian has probably speced what they think is the perfect strength/weight ratio for the 21" cast wheels to give them the overall mileage advantage.
 

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Glad to hear the 20's are forged, as that's what I configured the R1T with. From my understanding, forged wheels are superior in almost every way. Stronger, lighter, less prone cracking etc. The big downside is cost, as they are significantly more expensive to manufacture then cast/flow forming.

BTW, "Flow Forging/Forming" is really just a marketing term. They are cast wheels.
"Flow formed" is a little bit more than just a marketing term ("flow forged" however is very definitely a misleading marketing term). While still a cast wheel, flow forming is a significant improvement over gravity and low pressure casting allowing for considerable weight reduction of the barrel (which has the most impact on rotational inertia) vs a same sized wheel without otherwise compromising the structural integrity of the wheel.

Back in the day... I replaced the standard low pressure cast wheels from my 2004 BMW with a set of aftermarket flow formed wheels of the same size. Wheel weight dropped from approx 28 lbs per wheel to 18 lbs per wheel. Comparable forged options were within about a pound of the weight of the flow formed but substantially more expensive.

The porosity of cast wheels makes them prone to cracking from abuse that would otherwise bend a forged wheel. For serious offroad use, forged is definitely the better choice in terms of durability. For street (or light trail) use though, any form of cast wheel is a reasonable choice from a durability standpoint as long as you aren't trying to run low profile tires which often don't survive high speed encounters with deep pot holes or curbs. From a weight perspective in the context of BEV range, the different between forged and flow formed is relatively minimal and the weight difference could easily vary more based on the design of the wheel vs how they are formed. The price difference for forged though is still significant making it hard to justify the cost for the minimal weight savings over flow formed.
 

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I also came to a similar conclusion after reading up on the difference. What I still don't understand then is, how are the 21's still the configuration with the best range? Wouldn't the lower weight and rolling mass of the forged 20's make them better suited to delivering the best range, especially if paired with AS tires?
If AS and/or possibly a slightly smaller tire size than the stock ATs, I assume range would be very close to the 21s. Right now, we don't know how significant the range difference is between them today...

My hope was all sizes were forged. To pay a significant cost, say $3,500 for the dark 22" in cast, may just go with stock and then aftermarket?
For $3500, I would take the stock wheels and buy a completely separate set of wheels tires. You should come out cheaper than $3500, have exactly the styling you want, and have 2 sets of wheels/tires (or sell the stock ones & definitely stay well under $3500 net). Only downsides I can think is maybe getting a less aerodynamic wheel design & possibly more rolling resistance with off the shelf tires.
 

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Only downsides I can think is maybe getting a less aerodynamic wheel design & possibly more rolling resistance with off the shelf tires.
I would also add to that list the potential for increased road noise if the non-OE tire generates frequencies the Rivian is sensitive to (ie, are transmitted into the cabin).
 

skyote

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I would also add to that list the potential for increased road noise if the non-OE tire generates frequencies the Rivian is sensitive to (ie, are transmitted into the cabin).
Interesting. I would think most automotive insulation/sound dampening materials would handle a range of (most?) tire noise frequencies, but I admit zero knowledge here. Have you experienced that in other vehicles?
 

electruck

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Interesting. I would think most automotive insulation/sound dampening materials would handle a range of (most?) tire noise frequencies, but I admit zero knowledge here. Have you experienced that in other vehicles?
Many times... and again just recently actually. Replaced the factory Pirellis on my Volvo with a set of Michelins which ended up being noticeably noisier than even the worn out Pirellis (new tires are almost always quieter due to having their full tread depth; my prior experience has typically shown Michelin tires to be quieter than a similar Pirelli so this set of Michelin tires were a surprise for me).

Also keep in mind that the Rivian OE spec tires will almost assuredly make use of acoustic foam inside the tire which I suspect most non-OE tires in these sizes aren't likely to have at this point. That in itself could make a noticeable difference. Now that I'm thinking about it, I just took a look at the specs on my Volvo's factory tire and see they had Pirelli's PNCS acoustic foam - the new Michelins do not. That would appear to be the reason my new Michelin are noisier than my old Pirelli which goes contrary to my prior experience with the brands.
 

cohall

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Also keep in mind that the Rivian OE spec tires will almost assuredly make use of acoustic foam inside the tire which I suspect most non-OE tires in these sizes aren't likely to have at this point. That in itself could make a noticeable difference. Now that I'm thinking about it, I just took a look at the specs on my Volvo's factory tire and see they had Pirelli's PNCS acoustic foam - the new Michelins do not. That would appear to be the reason my new Michelin are noisier than my old Pirelli which goes contrary to my prior experience with the brands.
We have the foam-y tires on our XC60 as well. Interestingly, the OEM for us were Continentals, not Pirelli like yours. I wonder if it has to do with being in the mountains instead of TX?

Anyway, I hate them. The foam has a tendency to break loose inside the tire and cause a vibration though the car. We've already replaced 2 of our 4 original tires early because of it. I truly hope that the OEM tires on the Rivian are not the foam-lined variety.
 

electruck

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We have the foam-y tires on our XC60 as well. Interestingly, the OEM for us were Continentals, not Pirelli like yours. I wonder if it has to do with being in the mountains instead of TX?
More likely due to different sizes or just different production dates. I've got an R-Design with the 255/40-21 tires. Never had any problems with Pirellis over almost 40k miles.
 

cohall

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More likely due to different sizes or just different production dates. I've got an R-Design with the 255/40-21 tires. Never had any problems with Pirellis over almost 40k miles.
Makes sense. Mine is the Inscription with 20" ers.
 

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Many times... and again just recently actually. Replaced the factory Pirellis on my Volvo with a set of Michelins which ended up being noticeably noisier than even the worn out Pirellis (new tires are almost always quieter due to having their full tread depth; my prior experience has typically shown Michelin tires to be quieter than a similar Pirelli so this set of Michelin tires were a surprise for me).

Also keep in mind that the Rivian OE spec tires will almost assuredly make use of acoustic foam inside the tire which I suspect most non-OE tires in these sizes aren't likely to have at this point. That in itself could make a noticeable difference. Now that I'm thinking about it, I just took a look at the specs on my Volvo's factory tire and see they had Pirelli's PNCS acoustic foam - the new Michelins do not. That would appear to be the reason my new Michelin are noisier than my old Pirelli which goes contrary to my prior experience with the brands.
I also just changed out the well-worn Pirelli's on a used Volvo XC60 R-Design to Michelins, but went with the new Pilot Sport 4 S summer tire for light trucks and SUVs. I went for a set of Nokian LT3 Hakka's for the winter. Both sets seem quieter than the Pirelli’s, but I'm pretty sure the Pirelli’s were the second set. As such, they likely didn't have any acoustic foam inside. Having configured my R1T with the 20-inch wheels and A/T tires, reading this thread cements that choice for me, especially hearing about these wheels being forged.

Like others, I'm hoping to find safe, reliable, and less expensive options for a set of 22-inch performance wheels and tires, although the Rivian/Pirelli 22's would be preferred. It may be spendy to have a second full set, but I really like to get the most out of any vehicle, and my experience is that All-Season tires are good in all seasons, but great in none. Just like a decathalete has different shoes for different events, buying a great vehicle with the wide-ranging capabilities of the R1T & R1S, but not connecting them to a surface in the best way seems wrong.
 
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