245/60R17 vs 225/60R18

225/60R18 is 0.06 in (1.4 mm) taller than 245/60R17, a +0.19% diameter difference. With the speedometer set for 245/60R17, an indicated 60 mph is 60.1 mph on 225/60R18.

Is this a safe swap?

Diameter difference +0.19%: under 1%

By overall diameter alone, 225/60R18 is a near match for 245/60R17; 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.

245/60R17 vs 225/60R18 differences
Measurement	245/60R17	225/60R18	Difference	% diff
Overall diameter	28.57 in (725.8 mm)	28.63 in (727.2 mm)	+0.06 in (+1.4 mm)	+0.19%
Sidewall height	5.79 in (147.0 mm)	5.31 in (135.0 mm)	−0.47 in (−12.0 mm)	−8.16%
Section width	9.65 in (245.0 mm)	8.86 in (225.0 mm)	−0.79 in (−20.0 mm)	−8.16%
Circumference	89.77 in (2,280.2 mm)	89.94 in (2,284.6 mm)	+0.17 in (+4.4 mm)	+0.19%
Revolutions per mile	706	704	−1	−0.19%

True speed with the speedometer calibrated for 245/60R17
Indicated	Actual on 245/60R17	Actual on 225/60R18	Difference
30 mph	30.0 mph	30.1 mph	+0.1 mph
60 mph	60.0 mph	60.1 mph	+0.1 mph
75 mph	75.0 mph	75.1 mph	+0.1 mph

Ride-height change: 225/60R18 raises the vehicle by 0.03 in (0.7 mm) at the axle (half the +1.4 mm diameter difference).

225/60R18 is 0.06 in taller than 245/60R17 and 20 mm narrower, a 0.19% difference in overall diameter.

With the speedometer calibrated for 245/60R17, an indicated 60 mph is actually 60.1 mph on 225/60R18, and revolutions per mile change from 706 to 704.

225/60R18 mounts on a 18-inch wheel, a plus-1 fitment from the 17-inch wheel of 245/60R17.

Size pages

Other comparisons with 245/60R17

Other comparisons with 225/60R18

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