A right wifie question

[Sheilz]

If someone changes the size of their wheels does it affect the accuracy of the speedo and if so how can it be rectified?

[Gismo]

Normally when you increase your wheel size you put on lower profile tyres, which, overall bring the actual circumference to approx the same size as when you had the smaller wheels on
However, it's not exact and there may be a slight increase or decrease in the overall circumference, but, not enough to make the speedo read way out

There was a chart somewhere, martin will post it i'm sure ;)

[MartinSullivan]

This is (http://www.carbibles.com/tyre_bible.html) an interesting (YAWN!!!) site all about tyres etc , half way down it has a calculator which lets you input your original wheel/tyre combo - your new wheel tyre combo and calculate how far your speedo will be out.

The site is actually quite good , it explains a lot of things about tyres etc.

[Sheilz]

Cheers. Info is for one of my colleagues who has put bigger wheels on her motor. We were left with blank faces when contemplating this change in relation to speed limits n stuff. Will pass it on. Thanks.:D