Hi All, yea I am new here, but I would like to hope that I can contribute as much as I can help.
For starters, looking in the tire and wheel forum I have seen many posts where poeple were asking questions about different tire sizes and things like how much the speedo would change and teh like. well here is a TIRE SIZE CALCULATOR that everyone can use. you just put in the size of the tire you have as you stock tire, and then the size of the NEW tire you want to use. it will show you the NEW and OLD tires sidewall hieght, radius, diameter, circumferance, REV's/Mile, and at the bottom the Speedometer reading for the NEW tire, and how much difference it will make at 60 mph.
Hope this helps everyone.

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

 

sweet, i dunno if someones shown one before but thanks.

 

Joe, take a look over at the tech section of www.therangerstation.com too. You'll see many other calculators there.

Aaron

 

Hate to hi-jack the thread but...

Bridgestone says my tires do 722 Rev/Mile....that calculator says 698 so does the extreme tune software for my programer...any real difference between them? Which numbers should I use? Thanks!

 

I've always used the miata one, it's been good to answer quick questions here and there. However it may not account for a few things like sag from the weight of the vehicle, etc. Not sure how one could program this, but I';m sure it's possible. Over all I would side with bridgestone, but if you're just concerned with MPH calibration, use a GPS.

 

personally i hate the miata one this is the one i use constantly:
http://www.gordon-glasgow.org/tirecalc.html

its easy and quick