Open Competition Regulations 2026

OFFICIAL OPEN CLASS MINI 4WD COMPETITION RULES

Golden Rule:  All Tamiya Cars and parts only.

Tamiya's Mini 4WD competitions have established competition rules to ensure exciting races. These rules ensure fairness in terms of cars, courses, and competition content (competition methods and etiquette), allowing all competitors to compete under the same conditions.

The fun of Mini 4WD isn't just about speed. It's important to use your brain and technique to tackle the diverse courses available. These official competition rules will inspire a spirit of fair play and teach you the fighting spirit and etiquette befitting a true Mini 4WD racer. We ask all Mini 4WD fans to abide by these rules. Major

Tamiya-sponsored racing events also follow these rules, but special conditions will be announced in the respective participation guidelines.

The most important rule once again, ALL TAMIYA only!

1. ***ALL TAMIYA ONLY***. **This will be STRICTLY enforced through inspection before every race. If it is determined that a car contains "non-Tamiya" parts, the car and racer will NOT RACE that heat and will be considered as having lost the heat. While it is acceptable to paint parts, if the inspector’s are unable to identify that it is an original Tamiya part, the inspector may conclude that it is NOT A TAMIYA PART. The inspector's decision is final.
2. Two cars per racer only. We register the racer, not the car.  A racer can only register TWO CARS per category.  We may allow more than two car in certain races.  The number of cars allowed will be defined at registration.
3. Alkaline (1.5V) or Rechargeable batteries (1.2V) are allowed. Be advised that there may not be enough outlets in the venue. We will not be able to provide additional outlets. Please bring enough batteries.  

[1] COMPETITION CAR

1. TYPES OF COMPETITION CARS

Limited to Laser Mini 4WD, Mini 4WD REV, Mini 4WD PRO, Racer Mini 4WD, Super Mini 4WD, Fully Cowled Mini 4WD, Aero Mini 4WD, Mighty Mini 4WD, Radio Controlled 4WD, and Truckin' Mini 4WD series. Eligible car models and series may be limited depending on the competition and class.

2. COMPETITION VEHICLE SPECIFICATIONS

All competition cars must be four-wheel drive. Modifications to rear- or front-wheel drive are not permitted. The body must be attached securely to the competition car, and the body must be either stickered or painted (Note 1). Homemade bodies are not permitted. All competition cars must undergo vehicle inspection. Cars that do not pass inspection will not be allowed to participate. Competition cars must be assembled by the competitor themselves (Note 2). However, depending on the content of the competition, collaborative assembly may be permitted.

(Note 1)
To make it easier for competition officials to determine whether body modifications comply with the rules, cars that are significantly smaller or where stickers or paint are difficult to see may not be allowed to compete. Also, cut-out portions of clear bodies, wings alone, etc. are not considered "bodies."

(Note 2)
This does not apply to people who require assistance in daily life due to a disability or other reason.

3. Machine Measuring System

The dimensions of the racing car's body are regulated as follows: (Common to all chassis)
Racing cars must be four-wheel drive.
* Maximum width: 105mm or less
* Overall height: 70mm or less
* Overall length: 165mm or less
* Minimum ground clearance: 1mm or more
* Minimum weight with all equipment: 90g or more (including batteries and motor)
* Tire dimensions: Diameter: 22-35mm, Width: 8-26mm for both front and rear wheels (Tires must be installed)
* Roller equipment [Special rule]: The limit on the number of rollers has been changed from "6" to "unlimited" (this rule will continue to apply in 2025).

* Mass damper: The installation position of the rotating mass damper weight must be such that the entire weight is located inside the line connecting the center axes of the front and rear guide rollers.
* Mass damper [Special rule]: Along with the change in the limit on the number of rollers, there will also be no restrictions on the installation position of the rotating mass damper (this rule will continue to apply in 2025).

*The following restrictions apply to the mounting position of parts attached to the vehicle body.

- Parts must not be outside the outer edge of the tire, between the center axis of the front wheel and the rear end of the front wheel.

- Parts must not be outside the outer edge of the tire, between the center axis of the rear wheel and the front end of the rear wheel.

*The outer edge is defined as "the part of the tire that is located at the outermost position in the left-right direction."
*The rectangular pillar part in the illustration corresponds to the restricted area.

However, the body is not subject to these restrictions.
Additionally, there are no restrictions on parts that are only attached to the body, such as high-mounted rollers, as long as they are positioned higher than the center axis of the tire.

4. MOTOR

For competition cars,
in addition to the standard motor included with the kit, various Mini 4WD PRO motors can be used for driving with the MA and MS chassis.
Other chassis can use the standard motor included with the kit, as well as Torque Tune 2, Rev Tune 2, Atomic Tune 2, Light Dash, Hyper Dash 3, Power Dash, and Sprint Dash motors. (Torque Tune, Rev Tune, Atomic Tune, Hyper Mini, and Hyper Dash 2 motors are also permitted.)

1. Other Tamiya motors may be permitted depending on the competition event.
2. In competitions or classes with speed limits, motors cannot be used if they exceed the speed limit, even if they comply with the above regulations.
3. Illegal motor modifications, such as disassembling and changing the number of windings, are not permitted.
4. Any signs of the cup being removed from the motor's claws will be considered an illegal modification and will result in immediate disqualification.

5. BATTERY

Use two commercially available Tamiya AA batteries for the running power source (batteries other than Tamiya cannot be used).
*For safety reasons, batteries with torn battery labels are not permitted for use.
*Only Tamiya alkaline batteries can be used for the RC 4WD series and TR-1 chassis.
*Depending on the competition, there may be restrictions on the batteries that can be used, or batteries other than Tamiya may be allowed.

* For local races, rechargeable batteries may be used provided it has not been tampered.  Torn battery labels and replaced battery label are considered tampering.  Battery label must be original and not torn.

6. Modifications

Please follow the guidelines below when modifying your car. Also note that for modifications not listed, race officials will have the final absolute authority to grant or deny their use.

1. Chassis modifications are limited to cutting away plastic material or cutting holes out of the stock chassis. Homemade chassis are prohibited.
2. Parts used for modification are limited to Tamiya Mini 4WD, R/C Mini 4WD, and Dangun Racer parts only.
3. Part modifications are limited to cutting away the material or making holes in the stock part.

[NOTE]
The original part shape must be clearly identifiable.

In the following cases, it will be considered that the original part shape is NOT identifiable:
※Modifications to the shape of carbon plates, FRP plates or metal parts (including modifications to shaft, pin or roller shape).
※Using rollers and parts in prohibited combinations (putting plastic rings on rollers that do not use them; using plastic ring rollers without ring; using combinations of different sized rollers; cutting off one end of double rollers).
※Attaching HG aluminum setting boards, setting gauges and pinion pullers to the car.

In the following cases, it will be considered that the original part shape IS identifiable:
※Modifications to parts that keep the original part shape, such as simply cutting away the material, or enlarging or adding parts attachment holes.
※Opening holes or painting on the top side of the rollers.
※Modifying or cutting tire material (changing the material properties of the tire surface is prohibited. Combining different sizes or materials of tires is allowed. However, please make sure that they do not fall apart during running).
※Using motor parts is allowed (motor disassembly is not recommended).

4. Gear modifications are limited to making holes or shaving away material to reduce weight and installing ball bearings. All running gears must be installed according to the set gear ratios.
5. Only kit-included battery terminals or Grade-Up Part battery terminals, installed according to the instruction manuals, may be used. Soldering or double-plated terminals are prohibited.
6. Modifications that cause damage to the track, cause injury to any person, or release grease and/or other substances onto the track are all prohibited.
7. Modifications to the tire's shape are allowed if they comply with the Car Measuring System outlined above. However, changing the material properties of the tire surface is prohibited.

For courses which satisfy the below specifications and are sanctioned by Tamiya, times recorded during races will be officially recognized. All times recorded on original courses that do not meet these requirements will be considered unofficial.
• Individual lane width: 115mm (measured on a straight section)
• Course wall height: 50mm (measured from track surface)
• Adjusting the height and lane width of lane change sections, bank turn sections, etc. for smoother racing operations is permitted.

1. The start of the race will be indicated by a signal from a Tamiya race official or a starting signal system. Racers will switch on their cars, hold them in the air with one hand, and drop them vertically into their assigned lane at the start signal. Throwing or pushing the car forward is prohibited.
2. A racer will immediately retire from a race if their car leaves the track, flips over, jumps into another lane, or if their car's body detaches during the race.
3. If race officials determine that a racer's car is blocking the progress of faster machines, the racer will be required to retire.
4. A car's race is completed when it reaches the finish line.
5. Qualifying and Final positions are determined by either the race finishing order or Time Attack time.

1. All racers must have their car inspected by race officials before the race. If any part of the car is determined to be against race regulations, the racer must make the necessary changes in order to participate in the race.
2. From the time the car passes the car inspection to when the race begins, the car's settings must not be changed and no modifications can be made.
3. In addition to the pre-race car inspection, other car inspections may occur at any time during the race day at the race official's discretion. If the car is found to be in violation of the race regulations at any of these inspections, the racer's race results up to that point will be disqualified and the racer must make necessary changes in order to participate in subsequent races.
4. If a machine does not pass car inspection, and cannot be made race-legal, the participant can still take part in the Qualifying rounds for their own benefit, but their times will not be recorded.

If any of the following situations occur, race officials will, at their discretion, have absolute authority to disqualify any racer. Please take care to remember the common manners for a Mini 4WD race to avoid any problems.

1. A racer's car is determined to have modifications that will cause physical harm to other racers, other cars, or the race track.
2. A racer's car is determined to have modifications that are designed to deliberately obstruct other cars.
3. A racer deliberately puts grease or other substances onto the track to affect track surface conditions.
4. A racer is determined to have modified their car after it had passed the car inspection.
5. A racer is determined to have touched the track or cars to impede other racers' race progress.
6. A racer does not follow the instructions of race officials or otherwise impedes the operations of the race track.
7. A racer has a false start, or is determined to have thrown or pushed their car forward at the start of a race.
8. A racer is determined to have acted against the spirit of fair play or caused distress to other participants.

1. Please be aware that some races have age limitations, so it may be that some participants cannot take part in certain classes or races.
   2. Except for endurance races, it is against regulations to have more than 2 racers using the same car.