245/75R17 vs 285/60R18

285/60R18 is 0.00 in (0.1 mm) shorter than 245/75R17, a −0.01% diameter difference. With the speedometer set for 245/75R17, an indicated 60 mph is 60.0 mph on 285/60R18.

Is this a safe swap?

Diameter difference −0.01%: under 1%

By overall diameter alone, 285/60R18 is a near match for 245/75R17; 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.

245/75R17 vs 285/60R18 differences
Measurement	245/75R17	285/60R18	Difference	% diff
Overall diameter	31.47 in (799.3 mm)	31.46 in (799.2 mm)	0.00 in (−0.1 mm)	−0.01%
Sidewall height	7.23 in (183.8 mm)	6.73 in (171.0 mm)	−0.50 in (−12.7 mm)	−6.94%
Section width	9.65 in (245.0 mm)	11.22 in (285.0 mm)	+1.57 in (+40.0 mm)	+16.33%
Circumference	98.86 in (2,511.1 mm)	98.85 in (2,510.8 mm)	−0.01 in (−0.3 mm)	−0.01%
Revolutions per mile	641	641	0	+0.01%

True speed with the speedometer calibrated for 245/75R17
Indicated	Actual on 245/75R17	Actual on 285/60R18
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: 285/60R18 does not change the vehicle at the axle (half the −0.1 mm diameter difference).

285/60R18 is the same height as 245/75R17 and 40 mm wider, a 0.01% difference in overall diameter.

With the speedometer calibrated for 245/75R17, an indicated 60 mph is actually 60.0 mph on 285/60R18, and revolutions per mile change from 641 to 641.

285/60R18 mounts on a 18-inch wheel, a plus-1 fitment from the 17-inch wheel of 245/75R17.

Size pages

Other comparisons with 245/75R17

Other comparisons with 285/60R18

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