The Thunderdome rules
1/12 GTR 21.5 Rules
v1Class Rules1/12 GTR 21.5Effective Jul 28, 2026· Updated 3 months ago
Summary of recent changes
Current class specification.
Spec sheet
Governing
- Notes
- SXT 3.0 Medium (black cap) only; Snowbird Nationals 2020 rules; min 5 entries.
Motor & ESC
- Motor type
- Spec brushless
- Motor turn
- 21.5T
Tires
- Spec tire
- SJT rubber spec
- Tire additive
- Spec sauce only
1.Tires
SJT rubber spec tire.
2.Governing rules
SXT 3.0 Medium (black cap) traction compound only. Open ROAR racing spec motors. Snowbird Nationals 2020 rules apply unless superseded by class-specific governing bodies (USGT, U.S. VTA, Tamiya TT-02, etc.). Minimum 5 entries per class.
Version history
v1Published.
Jul 28, 2026