Need Tire Pressure Advice

[Radiate]

Newb to the board, but did try searching...
Snagged a nice 21 Willy's with 20 inch wheels and 35x12.5 Nitros. Not sure what psi to run the tires for normal driving. Currently at 40psi which seems a little high. Any folks with similar setups that could chime in? All of the info I found was for 17-inch wheels.
Bonus: how far can I air these down in sand without breaking the seal?
TIA

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[Aonar]

I typically run at about 13 PSI off road, as needed.
You will get lots of answers.

I also do the chalk test on all new tires to see what wears off the best. Currently when every-day-driving, I run about 27-29, when the tires heat up.


Just google chalk testing tires.

 

[JT1]

Newb to the board, but did try searching...
Snagged a nice 21 Willy's with 20 inch wheels and 35x12.5 Nitros. Not sure what psi to run the tires for normal driving. Currently at 40psi which seems a little high. Any folks with similar setups that could chime in? All of the info I found was for 17-inch wheels.
Bonus: how far can I air these down in sand without breaking the seal?
TIA

Since there is less air volume with the 20" wheel, I would drop pressure to 33 and see what it feels like. Nitto does have an inflation load capacity chart, you can look there too..

 

[azwjowner]

I typically run at about 13 PSI off road, as needed.
You will get lots of answers.

I also do the chalk test on all new tires to see what wears off the best. Currently when every-day-driving, I run about 27-29, when the tires heat up.


Just google chalk testing tires.

Your advice is sound for 17 inch wheels, but not for 20 inch, which will require higher pressures because of the smaller air volume in the tire.

 

[GATORB8]

20s push equivalent pressure up a bit. Assuming E loads, this is using the tiresize.com pressure calculator, which is a good starting point based on load capacity:

Since the load from the factory sticker is already high for efficiency, I'd try closer to 35 psi and see what you think.

https://tiresize.com/pressure-calculator/

 

[GATORB8]

Missed the bonus. I'd probably be comfortable on trail at 15. On sand probably less.

Do a trial run at the house and see where the contact patch spreads out nice and the tire bulges at the bottom.

 

[Aonar]

Your advice is sound for 17 inch wheels, but not for 20 inch, which will require higher pressures because of the smaller air volume in the tire.

Still a chalk test for daily driving, eh?

 

[azwjowner]

Still a chalk test for daily driving, eh?

That part, yes.

 

[Cips]

Chalk test!!!

 

[roaniecowpony]

There's already plenty of answers that cover pressure I'd probably use. But I'd be using a pressure below the TPMS warning threshold. So my recommendation is to get the JSCAN app, and the bluetooth adapter and harness, so you can lower the warning threshold to 25 psi to prevent nuisance warnings with cold weather. I think that's the lowest the system will allow you to adjust the warning. You'll still get the red warning while aired down for off-road.

 

[Ratbert]

Missed the bonus. I'd probably be comfortable on trail at 15. On sand probably less.

Do a trial run at the house and see where the contact patch spreads out nice and the tire bulges at the bottom.

I'd be nervous at 15 PSI with 20s. There's not much sidewall to protect the wheels.

 

[Radiate]

Thanks for all the great advice. Until I can get time for a chalk test, I aired down to 34psi to try out for a while. Living in Alabama, they'll gain 2-3psi just from the weather so may creep down a little lower in the summer. I'll post some results later on in case anyone else searches this in the future.

 

[Jmazz]

I have 35 x 12.5 x 20 MT Legends. I start at 29 psi cold. Like you said, in Florida here, they quickly go up to 32. No problem on the soft sand. Any higher and potholes will rattle your fillings loose. JSCAN for sure to enter tire height and TPMS setting

 

[mrtm1970]

I have 17s and 315/70R17 Falken Wildpeak AT3Ws and run at 34psi here in FL

 

[Radiate]

I just installed my JL mini to adjust pressures and size. How great that a tool like that exists. Had to go to the dealer anytime I changed anything on my old 4runner.

I have 35 x 12.5 x 20 MT Legends. I start at 29 psi cold. Like you said, in Florida here, they quickly go up to 32. No problem on the soft sand. Any higher and potholes will rattle your fillings loose. JSCAN for sure to enter tire height and TPMS setting

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