36psi all 'round.
On low-profiles (like 60 series), 44-46 psi seems best. On standard radials, they like 35-36. Best to stick with the tire pressure on the sidewall of the tire. Every tire is different (even if they are the same size, mfg and make).
Don't keep a low pressure as the tires will wear on the edges, high press will wear in the center. Either way, you lose a big bit of the contact patch, making your 225's act like 185's. Also, this makes the tires run hotter, wear faster and reduce handling. The Firestone tire brouhaha was related to this.