Instructions
Measure the size of your car's wheel well. This is the space cut out of the body shell that fits around the wheels. Measure the diameter of the wheels to avoid installing a tire that scrapes the body shell.
Select rims with the same diameter of the tires to help maintain their shape. The rim must be designed to function with your specific vehicle since they are generally categorized by fuel type (battery or nitro) and terrain (on or off road).
Count the number of teeth on your vehicle's pinion and spur gears. Divide the large number by the smallest to calculate the gear ratio. This number represents how many times the pinion gear spins, per rotation of the spur gear. Pick large tires if your ratio is a small number like 1:2. Pick smaller ones for a large ratio like 1:12.