dependant on tyres and rolling radius of the tyres, and engine power, would dictate the ratio.
I suspect a 3.62 would be better on current setup, would reduce wheels spin due to taller gearing and allow the 1st gear to be abit longer, on yours (and most tweaked Ti's) you end up snatching 2nd almost immediately which doesn't help traction. If you go for bigger rolling radius tyres (225/50 maybe) then a 3.9 will bring it back about right
if you go to 1Bs, you could be clever like the Keysers and run 13" wheels and tyres. 13" is the bastion of race cars and light 7-Types, so loads of sticky and usually reasonably priced tyres. other benefit is theres a whole range of rolling radius's. Beauty of a smaller rolling radius is that it does more rotations per mile, so gets warmer quicker (10% across ya average Curbs dbl lapper) and it lowers the car BUT crucially leaves the geometry the same as stock, unlike the normal method of lowering which buggers up the geometry, especially the rear.
for 13" 1Bs, look at Avon ZZRs, Yoko Ao48s, Toyo R888s in SG compound, Avon ACB10s, Kumho V70As (almost universal in Modprod as 'THE' tyre of choice). Its worth getting the motorsport tyre data sheets which give the actual sizes of tread width, rolling radius, etc, rather than the generic 185/60-13 etc which is just a guide size. Compound is everything, a wider tyre in the wrong compound wont be as effective as a narrower softer compound for our use in sprints/hills. Also hugely wide boots are draggy both in terms of bhp-sapping and aero drag at speed.
also think about tyre & wheel weights. Of the two the wheel is heavier, so a smaller wheel, with larger profile tyre will be lighter for the same rolling radius than a larger diameter wheel and lower profile tyre combo
remember this weight saving is x 4 times too...
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