Pro 12 Racing Class Rules

updated March 10, 2026

Class: Pro 12

DESCRIPTION: Pro 12 is an all new 2.2 spec tire class representing the smaller “1/12 to small end of 1/10” scale solid axle monster trucks. Currently the only known solid axle kit available with open differentials in this size is the HPI Big Kahuna 1/10 Monster King which is a rereleased and updated version of the HPI Wheely King and Crawler King. This class would *not* run with the modern 2.2 Class as the modern 2.2 class is mounting 2.2 wheels to super wide and long Pro Mod class trucks. LMT, Clod Buster, Freestyle RC axle and the like based trucks would not be legal in Pro 12.

Rules in beta: Rules are subject to change while we develop this new class and hear from racers and manufacturers.

MOTOR: One (1) 540 size motor. No turn limit.

BATTERY: One (1) 2s hard case lipo

CHASSIS: May be aftermarket, stock or scratch built. For exmple; the Team PRP Dim Mak chassis kit for the HPI Monster King.

SUSPENSION: 3 link )with or without panhard) or 4 link suspension. Sway bars may be used. No electronic assisted suspension or gyros are allowed.

TIRES/WHEELS:  Spec tire - stock HPI Monster King TRDZ with 2.2 inner/outer size wheels.

WIDTH: Maximum width is 13.5”

WHEELBASE: Maximum wheelbase is 12”

AXLES: Vehicle must be 4WD and have 2 solid Monster King/Wheely King/Crawler King axles with either 2 or 4 wheel steering. We imagine this can be updated if there are any similar size axles with open differentials available, like Tamiya CC02 for example.

TRANSMISSION: Ring and pinion style axles must have a centrally located, single speed transmission.

BODY: Any scale car or truck body is allowed.

OTHER: Electronic assisted suspension, 2-speed transmissions, disc brakes and one-way bearings are illegal. This helps keep costs down for both manufacturers and racers.