Specifically made to fit Viper V1™ and BSRT G3-R cars. Stiff chassis are usually the best for all Neo magnet cars for road racing. A stiff chassis is best for drag racing. It is recommend that you run custom "Rock" tires from Quicker Engineering for road racing. Slip-on style tires will not handle the potential speed of neo cars in road racing. Good road race formulas: Pro-35 traction magnets with Level 10 motor magnets and a 35G armatures in a stiff chassis; Pro-35 traction magnets and Level 4 motor magnets and a 36G armature in a stiff chassis.