Now Many of You have probably used this before...
I have... but lost it some time ago...

here is the link...
its excellent for checking tyre sizes etc....
You can use on Your VW,,
lots of different size tyres especially if You are running wider rims.

I did read somewhere that having too wide a tyre on the front of Your car is like wearing shoes too large for Your foot and the steering suffers likewise... Lee..

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

check how much Your speedo will be out on your front tyres.
and on the Rear ---

smaller tyres will increase Your acceleration.. but lower your top speed...

Larger diameter tyres will lower You engine revs at speed...
but can lower Your acceleration times...
depending on engine horse power & torque ...

cheers

LEE

1010 tyres is another good one

there is a few on the net that do the wheel as well as the tire, so it calculates guard and inner guard clearance compaired to the current wheel tire combo you have.


Just google wheel offset calc and you will find these.