Off-Road Tire Pressure?

[EVTrukHog]

I have 20"AT on my R1T. Door panel label specifies 48psi for road use. What is recommended pressure for off-road? Rivian recommended minimum for 20" is 31 psi. What do you use while off-road?

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[Sgt Beavis]

Considering the lower amount of sidewall on those 20" tires, I'd go with the 31psi recommendation. You run a chance of popping a tire bead if you go too low. I've run my Jeep as low as 20psi but those are 37" tires on 17" wheels. There is A LOT of sidewall to work with on those tires.

There are two purposes for deflation. One is to increase the tire patch size for better traction and the other is to give you a more comfortable ride when off roading by letting the side walls have more pliability. Increasing traction is definitely a benefit in many situations but consider those situations carefully before proceeding. Do you really need increase traction? Are you crawling over rocks, loose dirt, shallow mud, or even water fording. Then perhaps this is beneficial.

On the ride improvement side of things, I simply wouldn't do it. The R1's independent suspension and air shocks already do a great job of improving the ride on most off road surfaces.

i'm not advising you one way or another. Make your decision based on the off-roading scenario, but I do think you should stick with the psi minimum Rivian outlined.

 

[Inkedsphynx]

I'd agree with @Sgt Beavis but also reinforce the caveat that it really depends on conditions. On a well-worn forest service road, I'd only air down a little bit, maybe halfway between to 40psi. For any serious trail with big rocks/boulders, or any sort of slippery/watery situation I'd air down to the lowest I could go.

 

[W1SE]

There are two purposes for deflation. One is to increase the tire patch size for better traction and the other is to give you a more comfortable ride when off roading by letting the side walls have more pliability. Increasing traction is definitely a benefit in many situations but consider those situations carefully before proceeding. Do you really need increase traction? Are you crawling over rocks, loose dirt, shallow mud, or even water fording. Then perhaps this is beneficial.

Great post. I would even add a third reason to air down. I have had plenty of times when I have all the traction I need without airing down but I would pop a tire. By airing down you can protect your tires from punctures. Think of a balloon. When completely full it will pop much easier. But when you roll over sharp rocks you will be less likely to puncture the tire by letting it give a bit more. Slow or fast speeds.

This actually happened while going faster on a forest road. I didn’t air down and had highway pressure and hit a small 4-6” rock that popped the tire. I think I may have been better to have even 10 PSI taken out.

 

[Sgt Beavis]

Great post. I would even add a third reason to air down. I have had plenty of times when I have all the traction I need without airing down but I would pop a tire. By airing down you can protect your tires from punctures. Think of a balloon. When completely full it will pop much easier. But when you roll over sharp rocks you will be less likely to puncture the tire by letting it give a bit more. Slow or fast speeds.

This actually happened while going faster on a forest road. I didn’t air down and had highway pressure and hit a small 4-6” rock that popped the tire. I think I may have been better to have even 10 PSI taken out.

I agree with this. Though I’m not sure it will matter on the sidewalls of these Pirellis.

 

[k3g]

These sidewalls are pretty soft. This was at street pressure, in light sand with a few scattered rocks. Must have clipped one of them.

I aired down to 32psi after that, and stayed away from the sand that could hide more rocks like the one that gashed my tire. At 32 it feels perfect: The right amount of sidewall deflection, it dampens out the sharper impacts nicely.

 

[FrictionlessLube]

What’s everyone’s thoughts on the 21s” and off roading and a pressure to lower to? I plan on a somewhat moderate trail; I’d say maybe a 5/10 with a mixture of rocks. If anyone in Colorado is familiar, the off road trail to Fall River Reservoir.

Right now they are at about 47-48PSI once warm.

 

[mikehmb]

What’s everyone’s thoughts on the 21s” and off roading and a pressure to lower to? I plan on a somewhat moderate trail; I’d say maybe a 5/10 with a mixture of rocks. If anyone in Colorado is familiar, the off road trail to Fall River Reservoir.

Right now they are at about 47-48PSI once warm.

With the 21s, I’d try to stick with standard pressure (around 50 psi) unless you really need the extra grip. The lack of sidewall makes reducing the air pressure a little more sketchy.

I’ve got the 21s, and they’re adequate (even pretty good) for light-duty work, but if you’re up against sharp rocks or in the mud, things might get interesting.

 

[NashvilleR1S]

Dumb question, heading out today and realized I don't have a tire pressure gauge or anything to deflate the tires. Is there an easy way to deflate with the compressor kit to a specific PSI?

 

[KeithPleas]

Dumb question, heading out today and realized I don't have a tire pressure gauge or anything to deflate the tires. Is there an easy way to deflate with the compressor kit to a specific PSI?

I don't know about the compressor, but for my GX I use Staun deflators with speed clips. They won't help you with today's trip but nothing else comes close in terms of convenience.

 

[Dark-Fx]

Dumb question, heading out today and realized I don't have a tire pressure gauge or anything to deflate the tires. Is there an easy way to deflate with the compressor kit to a specific PSI?

Deflate and then reinflate.

 

[Sgt Beavis]

Dumb question, heading out today and realized I don't have a tire pressure gauge or anything to deflate the tires. Is there an easy way to deflate with the compressor kit to a specific PSI?

The kit does’t have a deflator. IMO, the best one on the market is from ARB. I also recommend getting spare tire stem valves (easy to replace) if you do any significant off road driving.

 

[Calvin2518]

Airing down to 30 PSI is perfect for off roading with the 20” rims. Gives the tires just a hair more room to compress and makes the ride a lot more comfortable.

Biggest complaint is that when parked, the PSI gauge on the truck shuts off after about 5 minutes so if you’re airing down or up- be quick if you want to rely on the gauge on the dash.

also @Sgt Beavis I found that the chuck to air up with if you attach just the chuck to the tire works incredibly well to air down with! Just need to keep an eye on the gauge on the dash to make sure you don’t air down too much.

 

[Zoidz]

I’ve been experimenting with pressure the past few days. Running in dry sand with no stone/rock and 20” ATs, I tried 35 psi one day and 40 psi the next day. Both had good traction, 35 psi was a bit smoother ride.

 

[usulio]

also @Sgt Beavis I found that the chuck to air up with if you attach just the chuck to the tire works incredibly well to air down with! Just need to keep an eye on the gauge on the dash to make sure you don’t air down too much.

Yeah, here's a video where someone shows this:




To approximate 30 PSI on ATs, I'd air down until the tread is basically flat on the ground, but the sidewall is not really bending inward. Edit: that description is probably too low. Even at 30 PSI the sidewall is not getting close to the ground, actually, it's not easy to see that they're aired down at all.

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