275/60R18 vs 285/60R18

285/60R18 is 0.47 in (12.0 mm) taller than 275/60R18, a +1.52% diameter difference. With the speedometer set for 275/60R18, an indicated 60 mph is 60.9 mph on 285/60R18.

Is this a safe swap?

Diameter difference +1.52%: within the ±3% guideline

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

275/60R18 vs 285/60R18 differences
Measurement	275/60R18	285/60R18	Difference	% diff
Overall diameter	30.99 in (787.2 mm)	31.46 in (799.2 mm)	+0.47 in (+12.0 mm)	+1.52%
Sidewall height	6.50 in (165.0 mm)	6.73 in (171.0 mm)	+0.24 in (+6.0 mm)	+3.64%
Section width	10.83 in (275.0 mm)	11.22 in (285.0 mm)	+0.39 in (+10.0 mm)	+3.64%
Circumference	97.36 in (2,473.1 mm)	98.85 in (2,510.8 mm)	+1.48 in (+37.7 mm)	+1.52%
Revolutions per mile	651	641	−10	−1.50%

True speed with the speedometer calibrated for 275/60R18
Indicated	Actual on 275/60R18	Actual on 285/60R18	Difference
30 mph	30.0 mph	30.5 mph	+0.5 mph
60 mph	60.0 mph	60.9 mph	+0.9 mph
75 mph	75.0 mph	76.1 mph	+1.1 mph

Ride-height change: 285/60R18 raises the vehicle by 0.24 in (6.0 mm) at the axle (half the +12.0 mm diameter difference).

285/60R18 is 0.47 in taller than 275/60R18 and 10 mm wider, a 1.52% difference in overall diameter.

With the speedometer calibrated for 275/60R18, an indicated 60 mph is actually 60.9 mph on 285/60R18, and revolutions per mile change from 651 to 641.

Both sizes mount on 18-inch wheels.

Size pages

Other comparisons with 275/60R18

Other comparisons with 285/60R18

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