Was going to make the tires our of RKT but what should I cover them with so i can make them detailed?
They just made a lot of tires on the Monster Jam episode of Ultimate Cake Off. You could probably go to the TLC website and watch the video. Or, one of the participants is a CC member and posted a thread about it with photos of the cake: http://www.cakecentral.com/cake-decorating-ftopict-672866-.html
She might have some tips in there, or you could pm her. HTH!