element.
3.5. Fuel injection may be fitted where it was standard equipment by the manufacturer for that engine type and where the original plenum chamber and throttle body is retained for that engine type.
3.6. A standard Wankel unit will be considered as three cylinders. Twin Wankel units are prohibited. Rotary engines are prohibited.
3.7. Engines must comply with the silencing Noise levels and have induction air filter elements fitted that ensure the vehicle complies with noise regulations. Engines must have induction air filter elements and exhaust silencers fitted that ensure the Vehicle complies with noise regulations established in Ch. 13 App. 1 Art. 7 at all times.
3.8. Only H shift pattern manual transmissions or standard equipment automatic transmissions in their original configuration are permitted. The gear lever must remain the only means of changing gear unless an alternative method was originally fitted by the vehicle manufacturer as standard. Automatic transmissions are permitted provided that they are in their original configuration as fitted by the manufacturer to that specific Vehicle model. and is retained unmodified.
3.9. The number and location of the driven wheels must remain as original to the model of Vehicle.
4. Wheels and Tyres
4.1. Wheels and tyre sizes are free but must fit within the standard unmodified wheel arch. All wheels and tyres fitted to a Vehicle must fit within the standard, unmodified external wheel arch profile.
4.2. The following wheel and tyre size restrictions apply:
Wheel Diameter Max. Wheel Rim Width Max. Tyre Width
Up to 13” 6” 185mm 14” 6.5” 195mm 15” 7” 205mm
16” and above 8” 225mm
4.3. Vehicles fitted as standard with wider wheel rims or tyres than those stated in the table in Art. 4.2 above may use their original manufacturer-supplied wheels. It is not permitted to use a larger wheel size( diameter and / or width) than that which was originally supplied as standard by the manufacturer for the make and model of Vehicle.
4.4. Vehicles must be fitted with tyres that are always legal for use on the Public Highway. 4.5. Tyres must comply with Ch. 8 App. 4 Arts. 2 – 3
4.4. Vehicles must have all spare wheels securely fastened in position and must not be fitted with spiked or studded tyres or any non-skid attachments other than chains if permitted by the Official Documents.
4.6. Vehicles must not be fitted with spiked or studded tyres or any non-skid attachments other than chains if permitted by the Official Documents.
4.7. A maximum of two spare wheels may be carried in competing Vehicles. All spare wheels must be securely fastened in position.
Motorsport UK National Competition Rules 2026 Edition 4
Chapter 22 Appendix 13 – Rally( Chapter 13) 807