Metric Tire Size Explained I think
01-31-2011, 06:16 AM
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JK Enthusiast
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Metric Tire Size Explained I think
I have been going nuts over the metric tire size thing and I went to my local discount tire and had the guy there explain it to me. It makes sense now but it is stupid overall since you have to do a lot of calculations to get actual size. So here it is for all to see.
315/70/R17 or X/Y/Z
X = Tire width in millimeters
Y = Side wall ratio to width.
Z = Rim size in inches.
so to figure out what it equals in inches.
Width in Inches = X / 25.4mm
Height in Inches = 2 * (Width in inches * Y%) + Z
Rim size in inches = Z
So for a 315/70/R17
315 / 25.4 = 12.4 Inches
(12.4 * .7) = 8.68 Side wall = 8.68 * 2 + 17 = 34.36 Height in Inches
I hope you guys can follow this. It is nice to know.
315/70/R17 or X/Y/Z
X = Tire width in millimeters
Y = Side wall ratio to width.
Z = Rim size in inches.
so to figure out what it equals in inches.
Width in Inches = X / 25.4mm
Height in Inches = 2 * (Width in inches * Y%) + Z
Rim size in inches = Z
So for a 315/70/R17
315 / 25.4 = 12.4 Inches
(12.4 * .7) = 8.68 Side wall = 8.68 * 2 + 17 = 34.36 Height in Inches
I hope you guys can follow this. It is nice to know.
01-31-2011, 06:39 AM
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That is great, I just type tire size conversion into google and use the Javascript program to do it. Not that I will need it again due to going to the great 15" wheel and 33X12.50X15's