Mini 4WD Official Race Rules (Tamiya)

Tamiya publishes official regulations for Mini 4WD races. This page is a beginner-friendly summary of the main points on Tamiya’s English regulations page. Individual events can add their own restrictions on machine types, motors and batteries, so always check the rules for the race you are entering.

Car size and weight limits

• Maximum car width: 105 mm
• Maximum car height: 70 mm
• Maximum car length: 165 mm
• Minimum ground clearance: at least 1 mm
• Minimum car weight: at least 90 g, including batteries and motor
• Front and rear tires: diameter 22 to 35 mm, width 8 to 26 mm. Tires must be attached.
• Rollers: there is no limit on the number of rollers.

Drive and body

• All machines must be four-wheel drive. Modifications that turn a car into rear-wheel or front-wheel drive are prohibited.
• Bodies must have stickers applied or be painted, and must be securely attached to the chassis.
• Home-made bodies are prohibited. A cut-off section of a clear body, or a wing on its own, does not count as a body.

Motors and batteries

Motors. Cars may use the kit-included normal motor, Rev-Tuned Motor, Torque-Tuned Motor, Atomic-Tuned Motor, Sprint-Dash Motor, Power-Dash Motor, Hyper-Dash 2 Motor, Hyper Mini Motor, Light-Dash Motor, Hyper-Dash 3 Motor, Rev-Tuned 2 Motor, Torque-Tuned 2 Motor and Atomic-Tuned 2 Motor.

• Mini 4WD PRO machines (ME, MA and MS chassis) may only use the kit-included normal motor or motors designed for the Mini 4WD PRO series.
• Taking a motor apart to change the number of coils, or similar illegal modifications, is prohibited.

Batteries.

• Only Tamiya-branded AA (R6/UM3) batteries are permitted.
• R/C Mini 4WD cars and TR-1 chassis cars may use alkaline batteries only.
• A battery that looks damaged, or has a damaged label, will not be accepted for safety reasons.
• Some events may have different rules on which battery types or brands can be used.

Allowed and banned parts

Allowed:

• Parts used for modification must be Tamiya Mini 4WD, R/C Mini 4WD or Dangun Racer parts.
• Chassis and part modifications are limited to cutting away material or cutting holes in the stock item.
• Gear modifications are limited to making holes or shaving material to reduce weight, and installing ball bearings. All gears must be installed according to the set gear ratios.
• Tire shape can be modified as long as the tires stay within the size limits above.
• Using motor parts is allowed (Tamiya does not recommend taking motors apart).
• Battery terminals must be kit-included or Grade-Up Part terminals, installed as the instruction manual shows.

Banned:

• Home-made chassis.
• Soldering or double-plated battery terminals.
• Changing the material of the tire surface.
• Modifications that damage the track, could injure someone, or release grease or other substances onto the track.

Race format

• Track: each lane is 115 mm wide (measured on a straight) and the walls are 50 mm high (measured from the track surface). Organizers may adjust lane change and bank sections for smoother racing.
• Start: a Tamiya race official or a starting signal system gives the start. Racers switch their cars on, hold them in the air with one hand and drop them straight down into their lane at the signal. Throwing or pushing the car forward is prohibited.
• Retirement: a car is out of the race immediately if it leaves the track, flips over, jumps into another lane or its body comes off. A car that officials judge to be blocking faster cars must also retire.
• Finish: a car’s race is complete when it reaches the finish line.
• Results: qualifying and final positions are decided by finishing order or by Time Attack time.

Inspection

• Every car must be inspected by race officials before the race. Anything found to break the rules must be fixed.
• Once a car passes inspection, its settings must not be changed and no modifications may be made before the race.
• Officials can inspect cars again at any time during the race day.
• If a car fails inspection and cannot be made legal, the racer may still run in qualifying for practice, but their times are not recorded.

Disqualification

A racer can be disqualified if:

• their car has modifications that could harm other racers, other cars or the track, or that are designed to obstruct other cars
• they deliberately put grease or other substances on the track
• they modify the car after it passed inspection
• they touch the track or cars to hold up other racers
• they ignore race officials’ instructions or disrupt the running of the event
• they false start, or throw or push their car forward at the start
• they act against the spirit of fair play or cause distress to other participants

Read the full rules

This is a summary only. Read Tamiya’s complete official regulations here: Tamiya Mini 4WD Regulations. The Japanese version is at tamiya.com/japan/mini4wd/regulation.html.