245/55R18 vs 225/60R18

225/60R18 is 0.02 in (0.5 mm) taller than 245/55R18, a +0.07% diameter difference. With the speedometer set for 245/55R18, an indicated 60 mph is 60.0 mph on 225/60R18.

Is this a safe swap?

Diameter difference +0.07%: under 1%

By overall diameter alone, 225/60R18 is a near match for 245/55R18; 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.

245/55R18 vs 225/60R18 differences
Measurement	245/55R18	225/60R18	Difference	% diff
Overall diameter	28.61 in (726.7 mm)	28.63 in (727.2 mm)	+0.02 in (+0.5 mm)	+0.07%
Sidewall height	5.31 in (134.8 mm)	5.31 in (135.0 mm)	+0.01 in (+0.3 mm)	+0.19%
Section width	9.65 in (245.0 mm)	8.86 in (225.0 mm)	−0.79 in (−20.0 mm)	−8.16%
Circumference	89.88 in (2,283.0 mm)	89.94 in (2,284.6 mm)	+0.06 in (+1.6 mm)	+0.07%
Revolutions per mile	705	704	0	−0.07%

True speed with the speedometer calibrated for 245/55R18
Indicated	Actual on 245/55R18	Actual on 225/60R18	Difference
30 mph	30.0 mph	30.0 mph	0.0 mph
60 mph	60.0 mph	60.0 mph	0.0 mph
75 mph	75.0 mph	75.1 mph	+0.1 mph

Ride-height change: 225/60R18 raises the vehicle by 0.01 in (0.3 mm) at the axle (half the +0.5 mm diameter difference).

225/60R18 is 0.02 in taller than 245/55R18 and 20 mm narrower, a 0.07% difference in overall diameter.

With the speedometer calibrated for 245/55R18, an indicated 60 mph is actually 60.0 mph on 225/60R18, and revolutions per mile change from 705 to 704.

Both sizes mount on 18-inch wheels.

Size pages

Other comparisons with 245/55R18

Other comparisons with 225/60R18

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