17. The brake kit from Spidertrax includes Wilwood Dynalite billet four-piston calipers and Polymatrix pads. The combination of large-diameter rotors and multi pistons works great with 40-inch tires on rock-racing buggies, and Spidertrax claims a 23-percent increase in braking versus a standard 113/8-inch rotor. The caliper stand must also be welded to the knuckle but it will clear under a 17-inch wheel. Smaller brakes are available for 16-inch wheels.