Wheels, especially the brakes, obviously, can get very hot. After lots of braking the rotors can get well over 1000° F. The tires should generally not get above about 195° F. The biggest thing is to check them occasionally and look for large temperature disparities. I carried one (Infrared Heat Gun) with me for a while to check the wheels once in a while, but many to check the left and right side of the radiator. You can check the radiator without a heat gun, of course. Get the engine up to operating temperature and if one side of the radiator is cool (ish) and the other side too hot to touch, you've got a blockage in there.
IIRC, Phil (A Team) carried a heat gun with him. Seen others use one out on the road. I mostly used mine in the kitchen for pan and griddle temps.