Is your speedo out because of your wheels?

[g00gz]

Was surfin the other day and came acroos this very handy link:

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

It lets you work out how far your speedo will / is out if you increase / decrease wheel size. Check it out!

[venomous]

yeh ihave 17's and my speedo is 12k's off.

now though its about 25k's of because i took my dash out and stuffed around with it lol.

[fu2]

my 225 60 r15 are .5kms off at 100kms