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How to know what the dimensions of your tire are in the European/Metric format

Discussion in 'General Jeep Discussion' started by OFFGRID, Nov 26, 2017.

  1. Nov 26, 2017 at 8:23 PM

    OFFGRID [OP] Well-Known Member

    Oct 3, 2016
    First Name:
    1979 Jeep CJ7, 258, TH350, NP208
    Howell fuel injection, header, HEI distributor, TH350, NP208, SOA lift with YJ springs in the front & GW springs in the Rear. AMC20 with G2 1 piece chromos trussed, Dana 30 with G2 chromos and 760x ujoints and MM Stainless Hubs, Geared 4.56. Tom Woods shafts, Metal cloaks, Caged, 37" Toyo MTs.
    I found an older post of mine that explains how to get the actual measurements of your tire in inches. This is for the new guys on our forum. Hope this helps. If it is unclear I could probably break it down further. Just plug and play your numbers into my equations below and you should be alright.

    Just for reference Your tires are 285/55/20. Looking at the marked tire above A,B,&C, A = 285 and references the width of the tire which is 285mm wide. B = 55 and references the height of the tire measured from the edge of the wheel to the top of the tire and is measure in a percentage of the width of the tire i.e.: 55% of A (285mm) which is 156.75mm. C = 20 and references the diameter of the rim which is 20 inches.

    Some formulas to get the dimensions of the tire.

    1in. = 25.4mm

    Width of the tire in inches: A = x mm / 25.4mm
    EX: 285mm/25.4mm= 11.22 inches wide.

    Height (overall) of tire: 2AB/25.4+C
    EX: 2 X 285 X 0.55 / 25.4 + 20 = 32.34 inches
    JKBob 25, Billy1234 and chris4x4 like this.
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