What PSI do you run for 35" MT tires on pavement? I just got the Pro Comp Xtreme MT (315/70R17).

Right now they are set at 28 psi. Is that too low? Do I need to set higher like 33 psi?

If yo have 315/70R17 or 35/12.50/17 tires on JK Unlimited, please post your current PSI.

Thanks!

 

You need to do a chalk test. Draw chalk lines accross all four tires and drive straight for 100 feet or soo and see how they wear. Adjust til you have a flat even pattern. @ 28 you should be pretty close. I have 35x12.5x18 nitto mud grapplers and i am at 26. (well I should be. They feel pretty soft right now so I probually didn't air up enough and they are probually at 18 )

 

Try starting about 27 front 25.5 rear and work from there.
.
.
.

 

This is correct for proper tire wear. Proper PSI may vary from one vehicle on 35's to another depending on wheel width. Also, If your concern is more about on-road handling than tire wear, you may want more pressure than someone else. The chalk test is a good way to start.

 

chalk tests? thats when gas was $1.00 per gallon. least rolling resistance is the best tire pressure for fuel economy. unless gas prices are cheap for you. forget about wear. you will spend more in gas than what a new set of tires will cost if you chalk your tires. i run 35 psi in m/t. try pushing your jk on flat level ground in neutral. adjust your pressure for the easiest to push. but hey thats my opinion. gas may be $1.00 per gallon in your area.

 

That is debatable and will depend on the cost of the tires, tread life of the tires, and the actual gain in gas mileage. Do you have any estimated numbers?

 

sure. a general rule of thumb. figure 10% in increased gas consumption for every 5 psi less than US D.O.T. approved tire pressure posted on the sidewall. off road or sand i am a very firm believer in lowered tire pressures. i run mine at 10 to 14psi off road. never lowered on road cause i can replace the tires at $225 per tire cheaper than one who on-highway tire pressure is 25psi which is 10psi less. or a 20% increase in fuel consumption. at the current gas prices do the math. also consumer reports and N.T.S.A has excellent info based on this info. but, hey you know what they say about opinions! and can you really trust the government?

 

Yea, but if you put too much air in you can cause a dangerous condition AND get worse tire wear. Big tires on smaller width rims will balloon so much they will ride on a skinny strip of tire in the middle. This causes twitchy steering, poor ride, and way too little contact patch on the road. You will have very little grip on the road. Things can get downright ugly on wet, snowy, or icy roads. Imagine a Jeep on 4 inch wide hard tires. Plus you will wear a strip down the middle. Sure you could save gas, but you could do that with any car or truck by pumping in way too much air.

A chalk test will give you a basis for setting your pressure. After a flat test, add 1 or 2 psi. That should give you a good mix of tire wear, traction, and fuel economy. My experience is that the best mix is just over the chalk test pressure. I figure it makes sense. The tires wear on the edges a bit when turning, so with rotations, a bit of center wear should work perfect.

 

I love this forum....I laugh so much while reading this stuff!!!

 

"too much air" than the recomended on the sidewall by the manufacturer. hell yeah. true. $ 2.50 per gallon for gas must be cheap for those who run underinflated tires. wow! I must be a tight-wad i want the least fuel consumption as possible. plus lower tire temps with properly recomended tire pressures. remember the firestone/ford fiasco? go ahead lower your tire pressures your life is on the line. take the gamble it MAY payoff.