17. Regulations for Open Wheel Single Seat Racing Cars 17.1. Dimensions
17.1.1.
Maximum width ahead of front wheels Maximum width behind front wheels Maximum height of any part wider than 1100mm ahead of the front wheels Maximum height
1500mm 1400mm Not to exceed the top of the front wheel rim
900mm from the ground Maximum rear overhang 1500mm behind rear wheel axis.
17.1.2. Maximum height is measured with the car in any condition and Driver aboard. Safety roll-over bars and air boxes are not included in this measurement.
17.2. Wheels
17.2.2. Twin rear wheels are permitted.
Motorsport UK National Competition Rules 2026 Edition 1
Chapter 14 Appendix 4- Technical Regulations 544