Alloys

[littlefitzer]

Hi all,
I am finally getting around to getting some alloys for my Bravo. I read somewhere though that getting a larger wheel can affect the accuracy of the speedo, so you have to compensate with the size of the tyre.
Can somebody please explain to me what tyre I would need to get (and which make is best) is I was to get 15 * 6.5 inch alloys, so as to keep the speedo accurate? The steel ones on the Bravo at the moment are 14 inch.

Also what exactly to the ratings on the tyre wall actually mean?

Thanks lads and lassies!

[Fergerino]

Howdy littlefitzer

Your speedo works on the assumption that one wheel revolution corresponds to a particular distance (the tyre's outer circumferance, or pi times outer diameter, to be exact). It follows that if you want your speedo to remain accurate, you need to ensure that the tyre's outer diameter remains unchanged.

Taking the example of a Bravo, the tyre is (I think) a 185/55R15. The numbers on the tyre are:
185 - The width of the tyre in mm from sidewall to sidewall.
55 - The percentage ratio of the tyre's height to it's width. In this case, the height is 185 X 0.55 = 102mm.
R - Radial construction
15 - Rim diameter in inches.

If you want a bit more info on tyre specifications, check out http://www.goodyear-malaysia.com.my/school/spec.htm

Hope it helps,

Adios
Fergerino

[littlefitzer]

Thanks Fergerino thats basically what I was looking for...good link!