Empirical evidence from running my TCH Bridgestone tire pressures at 42psi front / 40psi rear for the past 34,000 miles has led me to believe that Toyota has the recommended pressure set on the low side. I find the handling very good, even in the rain.

I say this as tread depth measurements on my tires have shown very even wear, with no evidence of premature center wear that would be expected if the tires where in fact over inflated. The tires measured 10/32 new, and currently measure 6/32 after 34,000 miles. The centers measure about 1/2 mm thicker than the edges. If anything, I think the higher pressure has extended the tire life as well as improved handling and MPG.

The few times the dealer has lowered the pressure to 32 psi during a service, I noticed the handling was markedly poorer, especially noticeable when cornering.