Infrared is a bit dicey with respect to tire temperatures. The critical temperature is deep within the tire at the belts. Temperature devices with pins that penetrate into the rubber are better for this sort of thing. In most areas of the country, the temperature inside the tire is usually much higher than the surface temperature. Then again, particularly in the southwest, the surface temperature can be much higher than internally. Infrared temperature gauges are fun but largely useless for tires
In the category of more information than you really want:
are cured (vulcanized) in the 310 to 360 deg. F range. However, the critical temperatures after curing is the temperature at which the rubber begins to revert. That is, when the adhesive properties begin to fall
off. As the tire spins down the road, the belts want to fly off. Only the adhesion of the belts to the body plies, and the tread to the belts keeps the whole thing together. As the tire heats up, it's heading directionally towards the reversion temperature. Normally, the tire sheds heat fast enough that you never get into the danger zone. Go fast enough, or run under inflated enough and the tire overheats, the adhesion degrades and centripital force throws the whole thing apart.
A variety of properties of the rubber stocks go into determining how well the belt/tread package stays attached. To stretch an analogy, rubber stock can have tear resistance properties that vary as much as rip stop nylon varies from a cheap pair of nylon stockings.
Because only the tire manufacturer knows the details of the rubber stock inside your tires, you'd have to select a very conservative number. However, in a parking lot in Arizona in the summertime, you'd get a temperature much higher than the desired internal temperature.