I need to know what the right tire pressure for 17's should be. My tires are 235/45. I have been running about 40psi, but it just seems like they should have a little bit more air in them. Anybody have any ideas?

 

man, 40 is kind of high. was that the pressure when the the tires were hot? stock is supposed to be 32 but i run 35psi all the way around, checked when the tire is cold of course. mine are 235/50/17.

 

You're probably right. My last ride was a 98 Prelude with 18's and I was running 40 series tires. I had to keep them at at least 40 psi.

 

The 32 Psi recommendation is from the ride engineers at nissan. For the craptenzas, 32 pounds is optimal for handling and grip. Wear is really bad though. I switched to michelin pilot sport a/s 235/50/17, and I run 40 lbs in the fronts and 35 in the rears. The way to tell if they are porperly inflated is to look at the contact patches. If the tires are at the right pressure, the contact patches should be right up to the edges of the horizontal tread, with no wear on the sidewalls.

The max tire pressure you should ever use is the "cold" rating on the sidewall. In my case, that is 51psi cold. Any more and the tire could be compromised. You must remember, the more inflated the tire, the less heat it makes. A tire running at 32 pounds makes more heat than one running at 40. This is simply because the sidewalls dont bend as much when the tire is rolling. As you already know, this bending is what causes the tire to heat up. The higher pressure tires wont get as hot, so the pressure wont go up as much. This is how you can run higher pressure.

The key to tire pressure is to get the optimal contact patch w/o going on to the sidewalls.