Here is one for the gurus. I have fitted 18" BBS wheels (RS11). They look great shod with SO2 tyres. With lower profile tyres than was on the stock wheels (still for sale)I reckon that the wheel/tyre diameter is 25" (versus 24") So by my old pythagarus (spelling??) the rolling circumference is 4% greater. Thus am I correct that my speedo will under read by 4%???? ( Got to watch the Feds and their blooming Gatsco's)
Here is one for the gurus. I have fitted 18" BBS wheels (RS11). They look great shod with SO2 tyres. With lower profile tyres than was on the stock wheels (still for sale)I reckon that the wheel/tyre diameter is 25" (versus 24") So by my old pythagarus (spelling??) the rolling circumference is 4% greater. Thus am I correct that my speedo will under read by 4%???? ( Got to watch the Feds and their blooming Gatsco's)