When I bought my vehicle it came with almost brand new Hercules Terra Trac A/T tires on it. They look very aggressive and are very nice. Only thing is I dont know the size of the tire. I know the rims are 15's but no where on the tire does it say its size. On the tire it does say 235/75R15

 

235 tire diameter in metric/75 aspect ratio width R type of tire 15 size of the rim opening

 

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I think he's trying to determine what it is in inches...

Doing the math, 1mm == 0.03937in

So the width is 235mm * 0.3937in/mm = 9.252in

75 is the aspect ratio, or the ratio of width to sidewall height, as a percentage.

So H_s == Height of sidewall = 9.252*75% = 9.252*0.75 = 6.939in

Now we know it's a 15" rim, but to get the overall tire diameter, you must double the sidewall and add the rim width.

Overall Diameter = 15 + 2 * H_s = 15 + 2 * 6.939 = 28.878in Which rounds out to the accepted 28.9in outside diameter that is the 235/75R15 tire.

If you don't feel like doing the math or unit conversions, I found a nice java utility a LONG time ago that would do it for you. You can also compare tire sizes.

Tire Size Calculator

 

Good job Kyle!.....this is a VERY common misconception: The first number is the width in millimeters...not the diameter.

 

swartlkk thank you so much. That was exactly what I was looking for, I really appreciate all you guys help. Thank you!

 

Not a problem, that's what we're here for!!!