TireSizesFinder

235/60R17 vs 285/45R18

285/45R18 is 0.00 in (0.1 mm) shorter than 235/60R17, a −0.01% diameter difference. With the speedometer set for 235/60R17, an indicated 60 mph is 60.0 mph on 285/45R18.

Is this a safe swap?

Diameter difference −0.01%: under 1%

By overall diameter alone, 285/45R18 is a near match for 235/60R17; 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: 235/60R17 (28.10 in) vs 285/45R18 (28.10 in)235/60R1728.10 in × 9.25 in285/45R1828.10 in × 11.22 in
Side profile and tread width, drawn to the same scale.
235/60R17 vs 285/45R18 differences
Measurement235/60R17285/45R18Difference% diff
Overall diameter28.10 in (713.8 mm)28.10 in (713.7 mm)0.00 in (−0.1 mm)−0.01%
Sidewall height5.55 in (141.0 mm)5.05 in (128.3 mm)−0.50 in (−12.7 mm)−9.04%
Section width9.25 in (235.0 mm)11.22 in (285.0 mm)+1.97 in (+50.0 mm)+21.28%
Circumference88.29 in (2,242.5 mm)88.27 in (2,242.2 mm)−0.01 in (−0.3 mm)−0.01%
Revolutions per mile7187180+0.01%
True speed with the speedometer calibrated for 235/60R17
IndicatedActual on 235/60R17Actual on 285/45R18Difference
30 mph30.0 mph30.0 mph0.0 mph
60 mph60.0 mph60.0 mph0.0 mph
75 mph75.0 mph75.0 mph0.0 mph

Ride-height change: 285/45R18 does not change the vehicle at the axle (half the −0.1 mm diameter difference).

285/45R18 is the same height as 235/60R17 and 50 mm wider, a 0.01% difference in overall diameter.

With the speedometer calibrated for 235/60R17, an indicated 60 mph is actually 60.0 mph on 285/45R18, and revolutions per mile change from 718 to 718.

285/45R18 mounts on a 18-inch wheel, a plus-1 fitment from the 17-inch wheel of 235/60R17.

Size pages

Other comparisons with 235/60R17

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