175/70R13 vs 185/70R13

185/70R13 is 0.55 in (14.0 mm) taller than 175/70R13, a +2.43% diameter difference. With the speedometer set for 175/70R13, an indicated 60 mph is 61.5 mph on 185/70R13.

Is this a safe swap?

Diameter difference +2.43%: within the ±3% guideline

By overall diameter alone, 185/70R13 falls inside the ±3% range commonly used as a guideline when replacing 175/70R13. 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.

175/70R13 vs 185/70R13 differences
Measurement	175/70R13	185/70R13	Difference	% diff
Overall diameter	22.65 in (575.2 mm)	23.20 in (589.2 mm)	+0.55 in (+14.0 mm)	+2.43%
Sidewall height	4.82 in (122.5 mm)	5.10 in (129.5 mm)	+0.28 in (+7.0 mm)	+5.71%
Section width	6.89 in (175.0 mm)	7.28 in (185.0 mm)	+0.39 in (+10.0 mm)	+5.71%
Circumference	71.14 in (1,807.0 mm)	72.88 in (1,851.0 mm)	+1.73 in (+44.0 mm)	+2.43%
Revolutions per mile	891	869	−21	−2.38%

True speed with the speedometer calibrated for 175/70R13
Indicated	Actual on 175/70R13	Actual on 185/70R13	Difference
30 mph	30.0 mph	30.7 mph	+0.7 mph
60 mph	60.0 mph	61.5 mph	+1.5 mph
75 mph	75.0 mph	76.8 mph	+1.8 mph

Ride-height change: 185/70R13 raises the vehicle by 0.28 in (7.0 mm) at the axle (half the +14.0 mm diameter difference).

185/70R13 is 0.55 in taller than 175/70R13 and 10 mm wider, a 2.43% difference in overall diameter.

With the speedometer calibrated for 175/70R13, an indicated 60 mph is actually 61.5 mph on 185/70R13, and revolutions per mile change from 891 to 869.

Both sizes mount on 13-inch wheels.

Size pages

Other comparisons with 175/70R13

Other comparisons with 185/70R13

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