Tyre ratings
Mister Towed, in another thread:
http://www.madabout-kitcars.com/forum/showpost.php?p=64943&postcount=1006
You gave some very helpful advice about tyre choices which is simply presented and to the point.
However, what do we do if there isn't an 'official' specification? Suitable for the purpose... How long is a piece of string.
My Marlin Berlinetta was 'available' in two broad specifications, 2 litre Ford Cortina with Cortina suspension, brakes etc., or Rover V8 3500cc, same suspension (wheels and tyres?) and brakes in both cases.
While the car is obviously more powerful in the V8 spec, I can not find any guidance in my build manual about the correct tyre sizes or ratings for either spec.
My simplistic logic suggests because the car is lighter, the amount of power and stress on the tyres will be less, even allowing for the fact that the V8 engine is more powerful. The original Cortina was just short of 1000Kg, a tad more with up to 5 occupants. The Rover SD1 V8 around 1,250Kg + up to 5 occupants. I estimate the Marlin will be 750-800Kg + 2 occupants, significantly lighter.
Where do I (and many other Kit car users) stand? The car was built in 1985, so a lot has changed in the sense of risk assessment and applied regulations. I suspect most of the Kit Cars of that era were designed on the back of a fag packet and in chalk on the works floor, Perhaps they still are???
My MOT garage takes the view that given most kit Cars are self build, provided they are well assembled, well maintained and not obviously dangerous, they are OK. Their standpoint is they are not qualified to state what specification should apply. They tend to apply the old maxim that if they would be prepared to use the car themselves, it should pass.
My own feeling is that using 185HR 14 or 205HR 15 tyres should be a reasonable choice, because the original Rover V8's were fitted with the 185HR 14 tyres.
