I run 32psi in the front and 36psi in the rear. Also, I dont think it matters how large the tire is, or how much 'room' you have - 35psi will be 35psi wether its in a car tire or a minivan tire. The only reason higher psi would be necessary in larger vehicles is purely because of the weight... I assume that a 225/40 tire with 35psi is equally as inflated as a 235/40 or a 205/55 -- after all, it's not the amount of air in the tire, its the pressure of the air in the tire...