Tire pressures can increase as much as 8 lbs on the highway depending upon speed and heat generated by the pavement surface.

 

That increase was already considered by the tire manufacturer when they spec'd out the max cold inflation pressure.

I run my TCH at 42psi front and 40psi rear. I've got the Bridgestone tires that are rated by Bridgestone for 50psi max cold inflation. I've noticed better handling, no noticable increase in road noise, and so far they are wearing even.