Alloy calculation

[Tonyw650]

Hey guys,
Is there a calculation you have to do for rolling circumference etc if you change alloys to keep speedo correct?
for example ive got the standard alloys on my v6 205/60/15's what would I need if I went for a larger wheel dia etc...

[jonsowman]

How's this? http://www.willtheyfit.com/

[lozz]

try nice wheels dot co dot uk etc

or here http://www.alloyguide.com/Peugeot.php

or just google alloy wheel guide,

[GingerMagic]

As a quick guide, although not 100% accurate, you can simply take 5 from the profile number to keep things about the same i.e.
205/60/15
205/55/16
205/50/17
205/45/18

This way you are gaining an inch on the rim size but loosing 5% of 205mm - which is approximately 10mm - so the overall difference is 15mm diameter increase per size upgrade.

[D9406]

Remember that the profile figure is for the tyre wall so you should double the 10mm to. 20mm and as an inch is 25.4mm the difference will be 5.4mm, less than one quarter of an inch in diameter.

[KozmoNaut]

I always use this handy calculator:

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