TireSizesFinder

37x13.50R18 vs 37x13.50R20

37x13.50R20 is 0.00 in (0.0 mm) taller than 37x13.50R18, a 0.00% diameter difference. With the speedometer set for 37x13.50R18, an indicated 60 mph is 60.0 mph on 37x13.50R20.

Is this a safe swap?

Diameter difference 0.00%: under 1%

By overall diameter alone, 37x13.50R20 is a near match for 37x13.50R18; the speedometer changes by less than 1%. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 37x13.50R18 (37.00 in) vs 37x13.50R20 (37.00 in)37x13.50R1837.00 in × 13.50 in37x13.50R2037.00 in × 13.50 in
Side profile and tread width, drawn to the same scale.
37x13.50R18 vs 37x13.50R20 differences
Measurement37x13.50R1837x13.50R20Difference% diff
Overall diameter37.00 in (939.8 mm)37.00 in (939.8 mm)0.00 in (0.0 mm)0.00%
Sidewall height9.50 in (241.3 mm)8.50 in (215.9 mm)−1.00 in (−25.4 mm)−10.53%
Section width13.50 in (342.9 mm)13.50 in (342.9 mm)0.00 in (0.0 mm)0.00%
Circumference116.24 in (2,952.5 mm)116.24 in (2,952.5 mm)0.00 in (0.0 mm)0.00%
Revolutions per mile54554500.00%
True speed with the speedometer calibrated for 37x13.50R18
IndicatedActual on 37x13.50R18Actual on 37x13.50R20Difference
30 mph30.0 mph30.0 mph0.0 mph
60 mph60.0 mph60.0 mph0.0 mph
75 mph75.0 mph75.0 mph0.0 mph

Ride-height change: 37x13.50R20 does not change the vehicle at the axle (half the 0.0 mm diameter difference).

37x13.50R20 is the same height as 37x13.50R18 and the same width, a 0.00% difference in overall diameter.

With the speedometer calibrated for 37x13.50R18, an indicated 60 mph is actually 60.0 mph on 37x13.50R20, and revolutions per mile change from 545 to 545.

37x13.50R20 mounts on a 20-inch wheel, a plus-2 fitment from the 18-inch wheel of 37x13.50R18.

Size pages

Other comparisons with 37x13.50R18

Other comparisons with 37x13.50R20

Source: Calculated from standard tire geometry formulas. Verified . How these numbers are calculated.