275/65R17 vs 285/60R18

285/60R18 is 0.39 in (9.9 mm) taller than 275/65R17, a +1.25% diameter difference. With the speedometer set for 275/65R17, an indicated 60 mph is 60.8 mph on 285/60R18.

Is this a safe swap?

Diameter difference +1.25%: within the ±3% guideline

By overall diameter alone, 285/60R18 falls inside the ±3% range commonly used as a guideline when replacing 275/65R17. 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.

275/65R17 vs 285/60R18 differences
Measurement	275/65R17	285/60R18	Difference	% diff
Overall diameter	31.07 in (789.3 mm)	31.46 in (799.2 mm)	+0.39 in (+9.9 mm)	+1.25%
Sidewall height	7.04 in (178.8 mm)	6.73 in (171.0 mm)	−0.31 in (−7.7 mm)	−4.34%
Section width	10.83 in (275.0 mm)	11.22 in (285.0 mm)	+0.39 in (+10.0 mm)	+3.64%
Circumference	97.62 in (2,479.7 mm)	98.85 in (2,510.8 mm)	+1.22 in (+31.1 mm)	+1.25%
Revolutions per mile	649	641	−8	−1.24%

True speed with the speedometer calibrated for 275/65R17
Indicated	Actual on 275/65R17	Actual on 285/60R18	Difference
30 mph	30.0 mph	30.4 mph	+0.4 mph
60 mph	60.0 mph	60.8 mph	+0.8 mph
75 mph	75.0 mph	75.9 mph	+0.9 mph

Ride-height change: 285/60R18 raises the vehicle by 0.19 in (5.0 mm) at the axle (half the +9.9 mm diameter difference).

285/60R18 is 0.39 in taller than 275/65R17 and 10 mm wider, a 1.25% difference in overall diameter.

With the speedometer calibrated for 275/65R17, an indicated 60 mph is actually 60.8 mph on 285/60R18, and revolutions per mile change from 649 to 641.

285/60R18 mounts on a 18-inch wheel, a plus-1 fitment from the 17-inch wheel of 275/65R17.

Size pages

Other comparisons with 275/65R17

Other comparisons with 285/60R18

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