155/80R13 vs 205/50R15

205/50R15 is 0.31 in (7.8 mm) taller than 155/80R13, a +1.35% diameter difference. With the speedometer set for 155/80R13, an indicated 60 mph is 60.8 mph on 205/50R15.

Is this a safe swap?

Diameter difference +1.35%: within the ±3% guideline

By overall diameter alone, 205/50R15 falls inside the ±3% range commonly used as a guideline when replacing 155/80R13. 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.

155/80R13 vs 205/50R15 differences
Measurement	155/80R13	205/50R15	Difference	% diff
Overall diameter	22.76 in (578.2 mm)	23.07 in (586.0 mm)	+0.31 in (+7.8 mm)	+1.35%
Sidewall height	4.88 in (124.0 mm)	4.04 in (102.5 mm)	−0.85 in (−21.5 mm)	−17.34%
Section width	6.10 in (155.0 mm)	8.07 in (205.0 mm)	+1.97 in (+50.0 mm)	+32.26%
Circumference	71.51 in (1,816.5 mm)	72.48 in (1,841.0 mm)	+0.96 in (+24.5 mm)	+1.35%
Revolutions per mile	886	874	−12	−1.33%

True speed with the speedometer calibrated for 155/80R13
Indicated	Actual on 155/80R13	Actual on 205/50R15	Difference
30 mph	30.0 mph	30.4 mph	+0.4 mph
60 mph	60.0 mph	60.8 mph	+0.8 mph
75 mph	75.0 mph	76.0 mph	+1.0 mph

Ride-height change: 205/50R15 raises the vehicle by 0.15 in (3.9 mm) at the axle (half the +7.8 mm diameter difference).

205/50R15 is 0.31 in taller than 155/80R13 and 50 mm wider, a 1.35% difference in overall diameter.

With the speedometer calibrated for 155/80R13, an indicated 60 mph is actually 60.8 mph on 205/50R15, and revolutions per mile change from 886 to 874.

205/50R15 mounts on a 15-inch wheel, a plus-2 fitment from the 13-inch wheel of 155/80R13.

Size pages

Other comparisons with 155/80R13

Other comparisons with 205/50R15

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