Discussion
The best size of tyre for any Mini (not the BMW Mini) is 165/70x10. Minis always handle best on 10" wheels and the vast majority of Minis used in Historic motor sport use 10", even when 12" would be allowed by the regulations. It is the size the car was designed for and the suspension geometry is right for this configuration. Also, the centre line of the tyres i.e. the rack width, should be as near original as possible to preserve the steering geometry.
Isn't an advantage of 12" over 10" wheels that you can get bigger brakes (e.g. MG Metro) under them - which aren't allowed in many historic series? Hence the handling advantage of the 10" wheels wins, whereas the better brakews possible with 12" wheels might otherwise be an advantage?
I use Cooper 'S' brakes because I have to under the historic regs. For pads I use Carbon-Metallic (from Mini Spares)and the fade resistance and wear are both excellent. Even on tarmac stages I don't get any fade so long as I use AP600 brake fluid. In fact for a Mini driven really hard you do need this fluid, and it's not cheap.
You can machine the larger calipers fitted on later cars down to fit under 10" wheels, but I don't have the details because it would not comply for competition.
For a history lesson, Paddy Hopkirk once used 12" wheels on the Circuit of Ireland Rally, but the car handled so badly he went back onto 10" as soon as he could. I doubt you would get a road-going Mini to out handle and out stop my 1964 Cooper 'S' on Yoko A008's on most road surfaces. It is a big mistake to try to set a Mini up like a racing car and then use it on the road. After 40 years of rallying I do know that a race set-up is really only good on a smooth track, but rally set-ups are great for ordinary roads.
I recently built a good engine for a chap with a 1974 1275GT. It gives 86 bhp at the flywheel, but he has fitted 13" wheels and when I drove it I thought it was really bad in the handling area. I think I have persuaded him to go to 10" after taking him out in my 'S' in the wet!
You can machine the larger calipers fitted on later cars down to fit under 10" wheels, but I don't have the details because it would not comply for competition.
For a history lesson, Paddy Hopkirk once used 12" wheels on the Circuit of Ireland Rally, but the car handled so badly he went back onto 10" as soon as he could. I doubt you would get a road-going Mini to out handle and out stop my 1964 Cooper 'S' on Yoko A008's on most road surfaces. It is a big mistake to try to set a Mini up like a racing car and then use it on the road. After 40 years of rallying I do know that a race set-up is really only good on a smooth track, but rally set-ups are great for ordinary roads.
I recently built a good engine for a chap with a 1974 1275GT. It gives 86 bhp at the flywheel, but he has fitted 13" wheels and when I drove it I thought it was really bad in the handling area. I think I have persuaded him to go to 10" after taking him out in my 'S' in the wet!
Very interesting post cooperman - I'd always been led to believe the 12" wheels and vented brakes were better due to the better braking, but I'm going with my gut feeling tha the bloke with 40 years experience rallying minis is more likely to be right 
Still keeping my 12s and MG metro brakes mind, as they're much cheaper than upgrading them
Still keeping my 12s and MG metro brakes mind, as they're much cheaper than upgrading them Gassing Station | Classic Minis | Top of Page | What's New | My Stuff