Diagram 67
Dimension B Height over front seats( measured between 0 ° and 15 ° towards the rear in relation to the vehicle using the test seat weight)
Dimension C Width for the front seats Dimension D Height over the rear seats( measured as Dimension B) Dimension E Width of rear seats. Dimension F Distance from the centre of the hub of the steering wheel to the brake pedal( if the steering wheel is adjustable it must be placed in the median position). Dimension G Length from the centre of the hub of the steering wheel to the bulkhead of the rear seat, or if possible to the rear face of the rear seat( maximum tilt 15 °) If the steering wheel is adjustable it must be placed in the median position. B and D are measured between the bottom of the seat compressed by the test seat weight, the axis of which is vertical, and the ceiling( padding compressed). If the seats are separate, the measurement is taken in the middle of each of the seats. In the case of longitudinally adjustable seats, the seats will be placed in the median position. If there is a bench seat in the front, the measurement is taken at 25cm from the centreline of the car. C and E are the maximum widths measured along the vertical plane passing through the axis of the standard test seat weights placed on the seats, being able to be freely maintained over a height of at least 25cm and a length of at least 40cm. The minimum dimensions( in cm) according to the cylinder capacity( in cm3) are the following, with H = F + G
Engine Capacity Dim. B
Dim. C
Dim. D
Dim. E
Dim. H
From 0 to 1,300 Free 90 Free 90 180
From 1,300 to 2,000
88 110 88 110 200
Over 2,000 93 120 93 120 210
Diagram 68 Diagram 69
Diagram 70
Motorsport UK 2025 National Competition Rules Version 11
Chapter 7 Appendix 13- Charts and Diagrams 315