38x13.50R20 vs 38x15.50R20

38x15.50R20 is 0.00 in (0.0 mm) taller than 38x13.50R20, a 0.00% diameter difference. With the speedometer set for 38x13.50R20, an indicated 60 mph is 60.0 mph on 38x15.50R20.

Is this a safe swap?

Diameter difference 0.00%: under 1%

By overall diameter alone, 38x15.50R20 is a near match for 38x13.50R20; the speedometer changes by less than 1%. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

Side profile and tread width, drawn to the same scale.

38x13.50R20 vs 38x15.50R20 differences
Measurement	38x13.50R20	38x15.50R20	Difference	% diff
Overall diameter	38.00 in (965.2 mm)	38.00 in (965.2 mm)	0.00 in (0.0 mm)	0.00%
Sidewall height	9.00 in (228.6 mm)	9.00 in (228.6 mm)	0.00 in (0.0 mm)	0.00%
Section width	13.50 in (342.9 mm)	15.50 in (393.7 mm)	+2.00 in (+50.8 mm)	+14.81%
Circumference	119.38 in (3,032.3 mm)	119.38 in (3,032.3 mm)	0.00 in (0.0 mm)	0.00%
Revolutions per mile	531	531	0	0.00%

True speed with the speedometer calibrated for 38x13.50R20
Indicated	Actual on 38x13.50R20	Actual on 38x15.50R20
30 mph	30.0 mph	30.0 mph
60 mph	60.0 mph	60.0 mph
75 mph	75.0 mph	75.0 mph

Ride-height change: 38x15.50R20 does not change the vehicle at the axle (half the 0.0 mm diameter difference).

38x15.50R20 is the same height as 38x13.50R20 and 51 mm wider, a 0.00% difference in overall diameter.

With the speedometer calibrated for 38x13.50R20, an indicated 60 mph is actually 60.0 mph on 38x15.50R20, and revolutions per mile change from 531 to 531.

Both sizes mount on 20-inch wheels.

Size pages

Other comparisons with 38x13.50R20

Other comparisons with 38x15.50R20

Source: Calculated from standard tire geometry formulas. Verified 2026-09-27. How these numbers are calculated.