Tire pressure and ride quality

[Ngkgb]

It has been unseasonably cold here in SoCal. Yesterday took the Rivian out and noticed ride quality was great. Seemed to absorb bumps better and overall just felt more confident. When I got back home, I checked the tire pressures and they were all at 45. I have 21”. I know range would take a hit to low tire pressure, but the ride quality was significantly improved. What other potential downfalls would there be?

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[Dark-Fx]

Uneven tire wear

 

[Ngkgb]

Uneven tire wear

If all tires are at same pressure?

 

[R1T Preds Fan]

Premature/excessive wear

 

[Madsen203]

I do this for our MY. Run at 36-37 rather than 42.

 

[madgrey]

Tires support the weight of your vehicle, if you reduce the pressure, the contact patch needs to increase proportionally, so you may be riding on parts of the tire not necessarily designed for that purpose.

 

[Riviot]

If all tires are at same pressure?

I run at 48psi cold on 20 ATs, but notice excessive middle wear (over inflated) by about 1mm. Once we're home from this road trip, I'll lower to try and counteract. I'll take a softer ride on my commute!

Get yourself a measuring device, you can get a couple for $10 from the big online retailer.

 

[jebinc]

Just installed 21’s for summer range. What is recommended cold pressure for these stockers?

 

[Cactusone]

The default factory tire pressure supports the MAX gross weigh. If you are light you can use lower pressure. Chalk test to confirm optimal pressure for weight configuration.

 

[mkg3]

The default factory tire pressure supports the MAX gross weigh. If you are light you can use lower pressure. Chalk test to confirm optimal pressure for weight configuration.

Completely agree.

Tire pressure is a function of loading so heavier the weight, higher the pressure to maintain proper contact patch.

I mostly ignore the tire pressure written on the manual. Also, I use different pressure for front vs back tires. Typically run 3 psi higher on the front tires for FWD/AWD ICE vehicles. It's mostly due to added weight of the engine up front. On my Model 3, I run rear tire pressure higher by 2 psi (41/43) since there is slight bias of weight to the rear AND my Md3 is RWD LR.

On R1S center of gravity (CG) must be near where the driver sits longitudinally since there are same motors at both axles. So the compromise is how often is the vehicle loaded with passengers and stuff in the back cargo area. Same logic applies to R1T, and the CG is probably almost at the same location even though the cabin weighs more than the bed, due to longer wheel base.

In both cases, I probably would run a slight bias towards the rear by 2 psi (assuming that passengers and cargo are aways present - otherwise run the same F/R). One would have to do some trial and error to see what works the best because it really depends on just how often and much of added weight (passengers and cargo) changes the weight distribution. In all cases, I would start around 45 psi and play it from there.

Last, higher the tire pressure, lower the rolling resistance so there is that too.

I had a friend years ago who drove a parade Caddy convertible (1973 Fleetwood??) and he used to run 20 psi on his tires for that soft cushy ride. He did replace his tires every 5k miles or so...

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