For those with oem 20's....
 

What does your sticker say on the inside door that you should set your tire pressure to?

Thanks.

35 psi F/R for the 275-55-20 pirellis

Would that apply to those of us that have larger tires? I'm running 275/60r20 and keep them at 35psi.

Look at the max psi on the tire sidewall. Don't use the door jamb sticker if you aren't using the stock tires. Most P-rated tires have a max PSI somewhere around 45-50, so just run something less than that. My LT tires will let me go up to 80psi, but I run around with 50psi in them.

Yeah I thought about going that route, but doesn't the weight of the vehicle play a part in using the correct psi? I could run the max psi in this tire in my 6000lbs f150, or on a much lighter ford ranger. I guess it's trial and error when you switch to a non-stock tire size.

If you look at the tire size you have, its a 275 wide just like the stockers, so it has the same footprint or contact patch with the road so the psi should be the same. Its when you change the width that everything changes.

B.T.W. I run 40 F/35 R in the stockers.

It really has little to do with the tire size. It has much more to do with the load rating and max pressure. A p series with a max of 35 or 44 should just about always be run at 35. Anything above 35 just helps with sidewall flex. A p series with a max of 50 would be run a bit differently.
An LT tire used on these trucks could be 3 different load ranges, LR C, D or E, which have 5 different max pressures. LR C will have a max of 50, a LR D will have a max of 50 or 65, and a LR E will have a max of 65 or 80. Each should be run at a different pressure. The LR C and the LR D max 50 should be run at about 40 with the C going up to about 45 range. The LR D max 65 and LR E max 65 should be run at about 45, and the LR E max 80 should be run about 50. None of these tires should be run lower than 40 and the LR E max 80 not below 45.

^ Good info kingfish. I only run mine at 50psi just for a little more room above the 45psi minimum on E-range LT's. With the stock goodyears I was running 35psi on all 4 corners.

Big slick, running the max PSI is what allows you to carry the greatest load rating for that tire. I don't run LT's because my truck itself it heavy, I run them because I occassionally tow heavy trailers and like the added safety of LT's with a heavy load on the hitch or in the bed. Stick with 35-40psi and you'll be good. You can run less in the rear if it gets too bouncy since there is less weight in the rear.

Running 305 50 20 Goodyear Wrangler GTII at 40-45 psi with max of 50 psi.

My coopers have a max pressure of 50 psi and I run them around 42 psi comfortably.

My tire guy who is our rep for my company told me the complete opposite. He said always go by the sticker and not by the tire psi (assuming near stock tire size). He said the tire psi rating is only for maximum loads, not just driving around. I have Goodyear Fortera's on mine slightly wider than stock 285/50/20's and he said go by whatever the door jam sticker tells you but I bought my trucks with 18's so I didn't know the rating.

Thanks for the info.

Yeah, I can't see how that would possibly be accurate as the engineers who specified the psi on the sticker have no idea what tire you are running after you have gone through the first set. 35psi is a good general pressure to run for most P-rated tires. Tires are designed differently and require different pressures for them to wear properly.

I would find another tire guy. Different load ranges mean different pressures. Running a LR E with a max pressure of 80 at 35 is good way to have a blowout and accident. If your truck came stock with that tire, the TPMS would be set to turn the light on at 46.

http://www.nhtsa.gov/cars/rules/ruli...ule.html?name=

Scott, how are the Coopers? I've been looking at these myself. How do they compare to the Perelli's?

I love them. They are fairly quiet for such and aggressive looking tire and they handle and ride great on and off road. I have around 20,000 on them now and they are not showing any signs of wear. I think I will get 50,000 out of them easily. I wouldn't hesitate to get another set. :thumbsup: