265/70R17 vs 285/60R18

285/60R18 is 0.14 in (3.6 mm) shorter than 265/70R17, a −0.45% diameter difference. With the speedometer set for 265/70R17, an indicated 60 mph is 59.7 mph on 285/60R18.

Is this a safe swap?

Diameter difference −0.45%: under 1%

By overall diameter alone, 285/60R18 is a near match for 265/70R17; 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.

265/70R17 vs 285/60R18 differences
Measurement	265/70R17	285/60R18	Difference	% diff
Overall diameter	31.61 in (802.8 mm)	31.46 in (799.2 mm)	−0.14 in (−3.6 mm)	−0.45%
Sidewall height	7.30 in (185.5 mm)	6.73 in (171.0 mm)	−0.57 in (−14.5 mm)	−7.82%
Section width	10.43 in (265.0 mm)	11.22 in (285.0 mm)	+0.79 in (+20.0 mm)	+7.55%
Circumference	99.29 in (2,522.1 mm)	98.85 in (2,510.8 mm)	−0.45 in (−11.3 mm)	−0.45%
Revolutions per mile	638	641	+3	+0.45%

True speed with the speedometer calibrated for 265/70R17
Indicated	Actual on 265/70R17	Actual on 285/60R18	Difference
30 mph	30.0 mph	29.9 mph	−0.1 mph
60 mph	60.0 mph	59.7 mph	−0.3 mph
75 mph	75.0 mph	74.7 mph	−0.3 mph

Ride-height change: 285/60R18 lowers the vehicle by 0.07 in (1.8 mm) at the axle (half the −3.6 mm diameter difference).

285/60R18 is 0.14 in shorter than 265/70R17 and 20 mm wider, a 0.45% difference in overall diameter.

With the speedometer calibrated for 265/70R17, an indicated 60 mph is actually 59.7 mph on 285/60R18, and revolutions per mile change from 638 to 641.

285/60R18 mounts on a 18-inch wheel, a plus-1 fitment from the 17-inch wheel of 265/70R17.

Size pages

Other comparisons with 265/70R17

Other comparisons with 285/60R18

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