Thanks so much Tanker! First, I have to give credit to Bronco for adding styrene wheels to the kit! I hate rubber tires! Now in terms of the effect, the rims were painted AK Modern Color and the tires were painted with AK Rubber. In terms of the actual weathering I gave the tires themselves a very very light drybrush of Mig Productions Dry Mud oil and the rims were given a wash of AK OEM wash and then I used Mig Productions Brown Wash oil for sponge chipping. Believe it or not I actually painted and weathered the tires twice. The first time they were "over weathered" and thanks to Ken Abrams I was able to see the error of my ways and do them again!