Originally Posted by Chowbow
You can inflate the tire to max psi, but that doesn't mean it's the correct pressure for running that tire, on this car, with the type of suspension setup on the car. On mine, I'm running 39F, 42R on 235/265 19s. I used this pressure after a bunch of driving and considered it to be a good pressure to go with in terms of cornering and braking. An overinflated tire will corner a bit better due to less roll over but you lose a lot in braking too... something I'm not willing to sacrifice on the street. At the autocross I'll go higher, 44F 46R.
The recommended tire pressure (either from the car’s manufacturer or the tire company) is shit. The numbers they give you are pretty much only for comfort. (Not performance, safety, or longevity)
You’re not “over inflating” your tires, you’re inflating them to the psi that gives you the best overall use of them, whether it be for performance OR safety.
With max psi and above you have:
1. Stronger sidewall
2. Better contact patch
3. Longer Tread life
4. More contact/traction in wet weather. (The faster you go the better contact your tires will have with the roads opposed to using the manufacturer’s recommended psi.)
5. Better handling
6. The only downside
to this is a harsher ride... thats all.
I've learned from racing instructors and all, but taking a stunt driving course opened my eyes to all the little things about tires. I learned a lot about tires, and a lot about cars and handling in general, so I’m just throwing my 2 cents in. Obviously you can’t inflate your tires to 50psi and start doing stunts in your E90, but I took this course, learned a lot, and will ALWAYS
keep my tires inflated to at least 5-10 above max psi.