ElpiAuto

Tire size comparison

325/60R20 vs 33X12.50R20

33X12.50R20 is 2.35″ (60 mm) shorter than 325/60R20, a 6.7% difference in overall diameter — outside the ±3% band, so expect the speedometer to drift and check for rubbing before fitting.

35.35″33.00″A  325/60R20B  33X12.50R20Both sizes to scale · dimension lines in inches
Measurement325/60R2033X12.50R20Difference%
Overall diameter35.35″33.00″−2.35″−6.7%
Section width12.80″12.50″−0.30″−2.3%
Sidewall height7.68″6.50″−1.18″−15.3%
Circumference111.07″103.67″−7.40″−6.7%
Revs per mile570.5611.2+40.7+7.1%
Revs per km354.5379.8+25.3+7.1%

Speedometer: with 325/60R20 as the original, 33X12.50R20 makes an indicated 60 mph really about 56.0 mph, and the axle sits ~1.18″ lower.

Reading this comparison

The overall diameter is what matters here: 325/60R20 is the taller tire. It sets ride height, gearing and how far the tire travels per revolution — which is what the speedometer and odometer count. Width and sidewall change fit and feel (a wider tire needs a wider wheel and more clearance; a shorter sidewall sharpens steering) but not the gearing.

Figures are geometric estimates from the size codes; real moulded tires vary by brand by 1–3%. Confirm load rating, wheel width and physical clearance on your vehicle before fitting. To compare any other two sizes, use the tire size comparison tool; to decode one size and see what else fits its wheel, the tire size calculator.

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