Hey guys I just bought two 315-35-17 summitomos for the rear and two 275-40-17 for the front anybody know what pressure these should go to for normal use? I've tried everywhere yet nobody knows. What pressure do you guys run with something like this? How about track use around what pressure?

 

What size wheels are these on?

 

I would start around 32 psi and work up from there. I run my 295 tires at 35.5 psi, my 275 tires at about the same, sometimes a pound or two higher since they are on the front.

 

If the 17's your using with those tires are 9" and 10.5" wide then I would keep them at 30. I had my last set at 32 and noticed a little more wear in the centers so i dropped it to 30. Make sure you keep an eye on the tires, you wanna get as much life out of the tires as possible esp when the tread is as soft as the Sumis are.

 

jeez, i feel like an idiot.. im running 40PSI in my 245/45 r17s on my machs! :O

 

Lol, there are tons of factors. Tire width/height, Wheel width/hieght. I have a stock set of Bullits (17x8) and run 245/45/17 on them. I keep them at 32.

 

well mine are oem machs,, at 17x8,, i have sumitomo all seasons on there too.. so we have basically same setup.. ill drop to 32.. prob make the tires have a better look too.

 

Well I spent about 4 hours yesterday night on the comp trying to find it about 3 am found this complicated *** formula where you factor in all these numbers like you said and the magic numbers were 32 for both. I had tried discount tire and the guy was like uhhh 35 psi. I just felt like >> for givin me sum good ol . And yes my rims are 9 and 10.5 rear. Some people even said do 40 I was like uhh seems too high. Thanks for the tip though I will keep it at 30 or maybe even 31. Those sumis are soft I broke em loose yesterday at about 10 mph going WOT and not even a screech. That takes the fun out of it. How about track use what PSI do you recommend?

 

Yeah you'll be hearing all kinds of numbers. You just have to kinda play around with it. From my experience, 32 was a tad to much because the centers wore more than the sides so i dropped it 30.

https://mustangboards.com/tire-wheel...-pressure.html - A couple ppl in their had the same experience too.

Yeah there soft, they just kinda mush though lol, its hard to get them to screech. I can get a chirp every now and then.

 

Well I would rather use the numbers that someone is giving me that has the same car same tires and rims bcuz chances are that those numbers are working good lol. Especially if 2 ppl say the same thing. I might go with something different once the sumis wear out bcuz whats the point of burning rubber if nobody can hear it. I wanna make that rubber screech LOL.

 

For street tires you don't need to change the pressure at the track. Because you should be using a pressure on the street that gives the best even wear and that's all you can ask out of a street tire.

 

I guess I'm running my pressures kinda high compared to you guys. It's that AutoX in me. I start my pressures out at 42psi at the course in optimal conditions (not cold or too hot, no rain).

 

thats what ive been running.. is it better to drop? its been snowing alot here.. and mud KILLS my car right now. even with the all season sumitomos and their 2 inch tread (not literally)

 

You need to drop the psi because you are way over inflating those tires and it will make the center wear out very fast. Plus you are missing the extra traction from not having a full contact patch from a correctly inflated tire.

 

So the psi that we been talking about is when tires are cold correct? Just thought i'd double check

 

That is correct...with heat comes more pressure.

 

im trying 35 in the front and 32 in the back.. so far it rides MUCH smoother!

 

For me to get them to wear even with 245's on a 17x8 wheel 30psi is what makes them wear even.

 

i use 30psi as well all around