I live in Phoenix, AZ and I keep my tire pressure at about 40 psi without any issues....

It can't get much hotter than it is here...

 

I think different tires give different ride characteristics at higher pressures. We've got Nokian WRG2's on in the winter months, and setting them to 45~ psi gives a fairly rough ride: they just don't give as much as our regular tires. The OEM Bridgestone Insignia's have a bit more flex at similar pressures. With the WRG2's I backed them down to 40, didn't seem that detrimental to mileage.

 

i run mine around 38-42psi depending on road conditions...too high of pressure works the suspension harder on rough roads. The slight loss in mpg is much cheaper than replacing struts or a bent rim, especially in the midwest here where potholes are common and roads are in terrible condition after our latest winter.