You have to be able to measure the tire deflection when the bike is loaded... over inflating your tires will have a negative effect on handling and impart a very harsh ride which will slow you down.

At 142 pounds I do not run any of my high psi tyres at their maximum as I find it decreases the performance of the bike.

With that being said I do run a MA40 front and am building up a matching rear for my fixed gear and feel confident that they could handle 120 plus psi with no issues even though I will probably be running them at 100-110 psi to adjust for my weight.