16'----->18'

[sars]

I currently have the stock rims(16') and 205/55/front & 225/50/rear tyres.

If I change the rims to 18' and 245/35 tyres, Is it necessary to adjust the speedometer or something else to make the speed and mileage shows correctly?

If yes, anybody knows where can I do it and for how much?

I'm in S.E Melbourne.

[DJ984]

as long as you keep the same rolling diametre she'll all be sweet... having said that... ask a wheel shop and they can direct you to places that can reconfigure speedo's etc if need be....

[sewid]

Use this if unsure http://www.inf.bme.hu/~zed/onlinetools/tyresize/

Anyway a 245/35R18 are actually 0.51% (average) smaller OD than 205/55R16.

The difference is so small that it doesnt matter.

[sewid]

With those stock size tyres, did your car come with the Active LSD? Thats what the factory put on Active LSD GTSts