Speedo reading altered?

[audia21991]

Hey, I was just wondering what would be the effect of changing from my basic wheels (lowest spec 15's) to my new 17's (205/40 ZR17) on the speedo reading? I haven't really noticed much difference but i'm sure there is a few mph in it, help please!!!:)

Old Wheels
http://img524.imageshack.us/my.php?image=a21xt4.jpg

New Wheels
http://img149.imageshack.us/my.php?image=a22oc9.jpg

[noodlefreak]

there are lots of calculators online.

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

[audia21991]

cheerz, but does anyone know the figures for the base 15"???? im afraid i haven't got a clue

[spike]

The standard tyres are 175/60/15"
Your new 17" wheels have an almost identical revs/mile figure so the speedo reading will be the same.

Cheers Spike