This is my first post and (I hope) a simple question. I have a 2005 WRX Sport Wagon that I purchased used. It came with 18" Racing Sparco wheels and a set of Hankook Ventas R-S2 225/40/ZR18 tires. I have searched several sites and have found a lot of good info on tires but still don't know what the cold pressure should be for this setup. When I first checked them they were anywhere from 52 to 38 psi. (From a dealer lot). I have settled on 35 for now but would like to know for sure.

Thanks
John

ive read on other forums that people like to run 40 psi but im not sure...

...try 39F and 36R....go up a pound or down a pound and that should get ya where ya want ta be ;)

I almost bought that car from Romain. It's a long story, but wound up with a new 2006 WRX silver wagon. I did test drive your car, it seemed to be pretty strong.
To your question, to keep the rolling radius the same front to rear, you need to find what the weight distribution is (52% front, 48% rear for example).
If you run 35LB in the front with the above weight split, you would probably want about 32LB in the back (48% / 52% ~ .92 take that x 35psig to get the rear pressure). I'm sure there is a better way to figure this but when I used to auto-x, thats the way I figured pressures. As always for public highway usage you want to stay within the tire mfg. recomendations.