1) I have 33 X 11.3 tires and by much testing and trial and error, I've established that they run best at 29 psi cold pressure tested in morning before driving. The local tire stores and also some online guys say they should run with 28 to 30 psi for my tires and vehicle weight (LJ Rubi). At 28 I get to much body roll. At 30+ it rides to rough. So 29 seems a good compromise for my 33 X 11.3 tires. Now your tires are wider, so I'd guess they run better at about 1 psi less than mine (just a guess).
2) I don't see how you could possibly fit 35 tires, unless you got the Highline Body Kit from AEV installed, which lifts and enlarges the fenders so that you can take 33" tires with no lift, 35" tires with 2" lift, or 37" tires with 3" lift, according to what users of that product have told me. Other than this kit, I don't see any way you're getting 35" tires on a Jeep with a 3" lift. AEV also sells wheels that are made to fit 35" to 37" tires on Jeeps with their Highline body kit and a 2" or 3" lift.
Also, the proper tire pressure partly depends on the relationship of wheel width to tire width. With an 8" wide wheel and a 33" x 12.5" tire, 28 psi sounds correct, but I run 29 psi cause my tire is 33" X 11.3" wide on an 8" rim.
If the rim were wider, say a 10" rim, then you could run a bit more pressure and still have a flatter foot print for better wear and street traction. So if you have a 10" rim with a 33 X 12.5 tire, then 30 psi, or perhaps even a bit more, is appropriate. The flatter footprint and higher tire pressure is why a wider rim in relation to the tire is better on street for street performance and fuel economy. This according to a couple of local tire stores in my area, and also what a wheel manufacturer tech told me on the phone.
However, the narrower rim holds a bead better when aired down off-road, as many at this very site have said many times.
We aren't making street rigs here, but I'm also not making a dedicated off-road rig either. I want the best all purpose, versatile, on and off road result. So that's one reason I prefer a medium width rim (like a 9" wide) cause then I can get a nice compromise between on and off road performance. Another reason I like a medium width rim is cause it suits my medium width tire preference (also for versatility).
Anyhow, the best tire pressure depends partly on tire size and vehicle weight. It also depends on the rim width, and depends on the load range of the tire. A higher load range tire on the same vehicle is a stiffer tire with stiffer side walls. So less air would probably be desirable when tire has a higher load range.
I think that for most Wranglers, a load range D tire is most appropriate. However, for anyone wanting the very most tear resistant sidewalls, then load range E. Personally, I'll stick with D because it rides smoother and is lighter weight than E. I don't care for load range C tires because I think the side walls are to wimpy even for trail use. However, my trails are wild. So maybe my view is skewed there.
Last edited by CB3; 05-13-2007 at 11:33 PM.