185/70R13 vs 215/50R15

215/50R15 is 0.27 in (6.8 mm) taller than 185/70R13, a +1.15% diameter difference. With the speedometer set for 185/70R13, an indicated 60 mph is 60.7 mph on 215/50R15.

Is this a safe swap?

Diameter difference +1.15%: within the ±3% guideline

By overall diameter alone, 215/50R15 falls inside the ±3% range commonly used as a guideline when replacing 185/70R13. 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.

185/70R13 vs 215/50R15 differences
Measurement	185/70R13	215/50R15	Difference	% diff
Overall diameter	23.20 in (589.2 mm)	23.46 in (596.0 mm)	+0.27 in (+6.8 mm)	+1.15%
Sidewall height	5.10 in (129.5 mm)	4.23 in (107.5 mm)	−0.87 in (−22.0 mm)	−16.99%
Section width	7.28 in (185.0 mm)	8.46 in (215.0 mm)	+1.18 in (+30.0 mm)	+16.22%
Circumference	72.88 in (1,851.0 mm)	73.72 in (1,872.4 mm)	+0.84 in (+21.4 mm)	+1.15%
Revolutions per mile	869	860	−10	−1.14%

True speed with the speedometer calibrated for 185/70R13
Indicated	Actual on 185/70R13	Actual on 215/50R15	Difference
30 mph	30.0 mph	30.3 mph	+0.3 mph
60 mph	60.0 mph	60.7 mph	+0.7 mph
75 mph	75.0 mph	75.9 mph	+0.9 mph

Ride-height change: 215/50R15 raises the vehicle by 0.13 in (3.4 mm) at the axle (half the +6.8 mm diameter difference).

215/50R15 is 0.27 in taller than 185/70R13 and 30 mm wider, a 1.15% difference in overall diameter.

With the speedometer calibrated for 185/70R13, an indicated 60 mph is actually 60.7 mph on 215/50R15, and revolutions per mile change from 869 to 860.

215/50R15 mounts on a 15-inch wheel, a plus-2 fitment from the 13-inch wheel of 185/70R13.

Size pages

Other comparisons with 185/70R13

Other comparisons with 215/50R15

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