ianbell

I got a bullshit ticket today for doing 62km in a 50 km zone - I'm damn sure I was only doing about 55 - 58 and the cop did only give me a 58 ticket. I have aftermarket 15" rims and am wondering if that effects the speedo reading as stock on my 87 n/a is 14". I know that taxis have to have their meters adjusted depending on the wheel and tire size - could the 1" wheel size difference with stock tires give a 10 % difference in the speedo reading?

NZConvertible

Wheel diameter is not important, the right tire diameter for your wheels is. What size are they?

Ryde _Or_Die

It all depends on how large the stock tire diameter is. If you have rims that are 1" larger than stock then u need tires that have 1/2" less of a sidewall to be equal.

FEDREX

http://www.miata.net/garage/tirecalc.html