TireSizesFinder

285/70R17 vs 265/70R18

265/70R18 is 0.10 in (2.6 mm) shorter than 285/70R17, a −0.31% diameter difference. With the speedometer set for 285/70R17, an indicated 60 mph is 59.8 mph on 265/70R18.

Is this a safe swap?

Diameter difference −0.31%: under 1%

By overall diameter alone, 265/70R18 is a near match for 285/70R17; the speedometer changes by less than 1%. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 285/70R17 (32.71 in) vs 265/70R18 (32.61 in)285/70R1732.71 in × 11.22 in265/70R1832.61 in × 10.43 in
Side profile and tread width, drawn to the same scale.
285/70R17 vs 265/70R18 differences
Measurement285/70R17265/70R18Difference% diff
Overall diameter32.71 in (830.8 mm)32.61 in (828.2 mm)−0.10 in (−2.6 mm)−0.31%
Sidewall height7.85 in (199.5 mm)7.30 in (185.5 mm)−0.55 in (−14.0 mm)−7.02%
Section width11.22 in (285.0 mm)10.43 in (265.0 mm)−0.79 in (−20.0 mm)−7.02%
Circumference102.76 in (2,610.0 mm)102.44 in (2,601.9 mm)−0.32 in (−8.2 mm)−0.31%
Revolutions per mile617619+2+0.31%
True speed with the speedometer calibrated for 285/70R17
IndicatedActual on 285/70R17Actual on 265/70R18Difference
30 mph30.0 mph29.9 mph−0.1 mph
60 mph60.0 mph59.8 mph−0.2 mph
75 mph75.0 mph74.8 mph−0.2 mph

Ride-height change: 265/70R18 lowers the vehicle by 0.05 in (1.3 mm) at the axle (half the −2.6 mm diameter difference).

265/70R18 is 0.10 in shorter than 285/70R17 and 20 mm narrower, a 0.31% difference in overall diameter.

With the speedometer calibrated for 285/70R17, an indicated 60 mph is actually 59.8 mph on 265/70R18, and revolutions per mile change from 617 to 619.

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

Size pages

Other comparisons with 285/70R17

Other comparisons with 265/70R18

Source: Calculated from standard tire geometry formulas. Verified . How these numbers are calculated.