Specifically made to fit Viper V1™ and BSRT G3-R cars. Stiff chassis are usually the best for all Level 25 and higher magnet cars for road racing. A stiff chassis is best for drag racing. It is recommend that you run firm slip-on tires such as Super Tires in compound "B" on a quality aftermarket hub or custom "Rock" tires from Quicker Engineering. An all Level 25 road racing car needs a 35G armature.