Join Date: Sep 1999
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Re: Tires size, mileage and daily driving...
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<font color=green>Drey, your perception of how tires are measured is a bit off, but 94GMC's has a small bit of misinformation too (the first number is the tread width, not the width at the bead, maybe that's what you meant, but it was kinda confusing[img]images/icons/wink.gif[/img]). Here is how it works. Example is for a 235/75r15.
235 is the tread width in mm. 75 is the aspect ratio, which means that the height of the sidewall is 75% of 235. 15 is the rim size. To figure out how tall the tire is in inches, the formula is ((235*.75*2)/25.4)+15=28.9" tall. 25.4 is the number of mm in an inch, the rest of the formula should be self explanatory.
Or you could do it the easy away and go here - <a target="_blank" href=http://www.4lo.com/4LoCalc.htm>http://www.4lo.com/4LoCalc.htm</a>