Hey, I just wanted to know what level of psi should I have on my 235/40/18 tires... currently from the tire installer they are set at 40... and Im guessin thats way to high...

 

i would start at 33 to 35 and go from there... size of tire does not matter contact patch does..

beers

 

yes, if it is for daily driving about 35 is the average.

otherwise:
decrease tire pressure = increase grip
increase tire pressure = decrease grip

up to certain degrees that is.

 

32 cold, I ran 35 cold for a while and noticed the middle was wearing a lot more than the edges even with aggressive camber and autocrossing on them.

 

well im about to do a 5 hour drive, so I guess i'll set them at 34psi

 

I'm bone stock and I noticed the same thing. They were at 34psi early April, so probably gained a couple psi as it gets warm to about 36psi. the middle wear a lot more even before my track day. It's back to 32 now, and it ride so much better. Of course they were pretty worn to begin with, so off to my new tires...

 

Weird. ... I've been running higher pressures (38 -40) and find the outer edges are more worn than the inside. (still have the stock Dunlops)

 

I have been running at 37psi on my OE Dunlops. Also the factory alignment. I have not had a problem yet.

 

Kumho Ecsta SPT 225/45R18 at 35PSI.

 

Bridgestones Potenza RE050A with 35 front and 34 rear. Works great. No abnormal wear on any corner.

 

i believe your kumho can handle a litttle more im in the 40'S. look at the max tire pressure