Hey guys... I found this on the net for those people interested in knowing how the aftermarket tires they choose will effect their speedo..

It can be yours for only 3 easy payments of 19.95.... jk... :) I thought I better edit this before people start believing me..

Check out the link...

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

Alllsooo... This.....

http://www.mindspring.com/~toy4two/tire.html

Both are excellent....

Hope this isnt a re-post..

Thankx!

The second one's my favorite. Very helpful.

-Mr. Wigggles

My favorite at:

Another Tire Calculator (http://www.csgnetwork.com/tireinfo4calc.html)

My favorite at 1010 Tire, actually shows a pic of the tires for comparison.

Here (http://www.1010tires.com/TireSizeCalculator.asp).

Omicron,

I like the 1010 site except for one thing. When they resize the tires the also resize the rims in the process. A 145/25-18 will have totally different rim size compared to a 355/95-18. Put the values in for a pretty funky picture.

It gets the overall tire diameter correct but it doesn't get wheel quite right.

Otherwise it is a really cool visual display.

-Mr. Wigggles

Didn't know that... helpful info, thanks.

the best way to get this info is from the tire manufacturers websites... any other way is just a calculation made with a few assumptions that the tire is exactly the size on the sidewall (not always exactly the case)