11. Recommended Classes
11.1. Along with the mandatory Historic Road Rally Classes requirements classes can be introduced based on capacity and / or age of Vehicle. It is recommended that they be the same as for Historic Stage Rallies.
11.2. Certain waivers may be available for Historic Road Rally Cars entered in Road Rallies and Rallies with Special Tests solely for vehicles manufactured before 31st December 1946.
11.3. The ASN may also grant discretionary waivers for Historic Road Rally Cars complying with Art. 9.2 above in respect of Arts. 3.1 – 3.4 above as appropriate for Road Rallies and Rallies with Special Tests held between 07.00 and 22.00hrs providing an Historic Grade Eligibility Scrutineer is appointed.
11.4. Application for waivers must be made to the ASN by the Organisers of the specific Event giving full details of the waivers sought.
11.5. Any such waivers will be exclusive to an individual Motor Club and the nominated Event.
11.6. Exceptionally the ASN may grant a written dispensation to use non-original parts from a different model or parts from a later period provided that the use of these parts does not confer an advantage in either performance or reliability and the Decision of the ASN is final and not susceptible to any form of Appeal. The ASN will consider written requests from Competitors who are unable to source vital components.
12. Engine
12.1. Forced induction is permitted if by means of a mechanically driven supercharger or by an exhaust driven turbocharger if fitted as original equipment by the Vehicle manufacturer. Such Vehicles will be classified as having an engine capacity increased 70 %.
12.2. Induction air filter elements must be fitted that ensure the Vehicle complies with noise regulations.
12.3. Exceptionally and with the permission of the Chief Scrutineer those Vehicles for which 5000rpm is inappropriate may be tested at 3 / 4 of maximum rpm.
13. Wheels Tyres and Brakes 13.1. Vehicles must always be fitted with tyres that are legal for use on the Public Highway.
13.2. The size of the wheel may not differ from that originally fitted by more than 10 % on nominal diameter and / or by 1 inch( 25.4mm) on nominal width.
13.3. Vehicles originally fitted with 10 inch diameter wheels may increase to 12 inch diameter wheels. 13.4. The minimum diameter permitted is 15 inches unless a smaller diameter was fitted as original equipment.
13.5. The tyre section as marked on the side wall in millimetres or inches must not differ by more than 1 inch( 25.4mm) from that originally fitted.
13.6. The fitting of tyres with an aspect ratio of less than 65 % is prohibited.
13.7. The fitting of a dual master cylinder or any other type of device providing a simultaneous action on all four wheels and divided action on two wheels is permitted provided the original brake pedal and pivot point are used and it must be possible under all conditions, running or stationary, for 25 % minimum braking effort to be applied by the driver through the braking system to each axle. For Cars in Category 1 the adjustment of brake balance must not be possible by either the Driver or the Co-Driver when normally seated in the car.
13.8. A hydraulic handbrake is permitted where a functioning mechanical system is also present. The hydraulic handbrake lever shall operate in an arc not exceeding 50 degrees from the horizontal( See Drawing 1 App. 23).
13.9. For Vehicles in Categories 2 or 3 or 4 Art. 13.6 does not apply where OE specification tyre aspect ratios are less than those specified therein.
Motorsport UK 2025 National Competition Rules Version 11
Chapter 13 Appendix 15- Technical Regulations- Road, Endurance and Historic Road Rally Cars
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