i dont think its your wheels, as you need to have a damaged or buckled wheel to get that kind of feeling, and it would do it all the time and affect your steering, not just when its hot. your rotors would be warped due to very high brake tempretures, the standard rotors cant disperse the heat and gas the way that slotted/vented rotors can. if you upgrade, go the DBA 4000 rotors and Bendix Ultimate pads, which you can get from Repco or anywhere like that....