Justin, tires (tyres for Eion) are a problem for the very high speed or very heavy (3500 lbs+)cars. Goodyear makes severial "land speed" tires that will fill a lot of classes. All but one is based on the drag race "front runner" mold with extra side wall added. They come in 21.3, 23.1, 24.8, 25.4, & 27.8 inch dia. Max load per tire veries but it is around 1500 lbs per tire. Some folks with small or light cars use the drag race front runners with good results.
As for the very fast (280+) we are just begining to hear of the problems getting good tires.
Mike