about wax and heat, your paint can reach high temps sitting in the sun and wax is used to protect the paint from fading.

when your car is moving a flow of air over the outter wheel I would think keeps the surface warm enough to prevent the wax from evaporating.

I actually coat the inside of my wheels with petroleum jelly to act as a barrier and protectant for the inner wheel surface. Once a year or so I clean the inside of the wheel and the petroleum jelly wipes clean with some effort but leaves a surface easier to get shiney than without any protection.

In hot wet conditions the petroleum jelly may migrate to the outside of the wheel but only a few inches and always from the brakes.