225/60R17 vs 245/50R18

245/50R18 is 0.02 in (0.4 mm) taller than 225/60R17, a +0.06% diameter difference. With the speedometer set for 225/60R17, an indicated 60 mph is 60.0 mph on 245/50R18.

Is this a safe swap?

Diameter difference +0.06%: under 1%

By overall diameter alone, 245/50R18 is a near match for 225/60R17; 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.

225/60R17 vs 245/50R18 differences
Measurement	225/60R17	245/50R18	Difference	% diff
Overall diameter	27.63 in (701.8 mm)	27.65 in (702.2 mm)	+0.02 in (+0.4 mm)	+0.06%
Sidewall height	5.31 in (135.0 mm)	4.82 in (122.5 mm)	−0.49 in (−12.5 mm)	−9.26%
Section width	8.86 in (225.0 mm)	9.65 in (245.0 mm)	+0.79 in (+20.0 mm)	+8.89%
Circumference	86.80 in (2,204.8 mm)	86.85 in (2,206.0 mm)	+0.05 in (+1.3 mm)	+0.06%
Revolutions per mile	730	730	0	−0.06%

True speed with the speedometer calibrated for 225/60R17
Indicated	Actual on 225/60R17	Actual on 245/50R18
30 mph	30.0 mph	30.0 mph
60 mph	60.0 mph	60.0 mph
75 mph	75.0 mph	75.0 mph

Ride-height change: 245/50R18 raises the vehicle by 0.01 in (0.2 mm) at the axle (half the +0.4 mm diameter difference).

245/50R18 is 0.02 in taller than 225/60R17 and 20 mm wider, a 0.06% difference in overall diameter.

With the speedometer calibrated for 225/60R17, an indicated 60 mph is actually 60.0 mph on 245/50R18, and revolutions per mile change from 730 to 730.

245/50R18 mounts on a 18-inch wheel, a plus-1 fitment from the 17-inch wheel of 225/60R17.

Size pages

Other comparisons with 225/60R17

Other comparisons with 245/50R18

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