TireSizesFinder

225/75R17 vs 255/60R18

255/60R18 is 0.24 in (6.1 mm) shorter than 225/75R17, a −0.79% diameter difference. With the speedometer set for 225/75R17, an indicated 60 mph is 59.5 mph on 255/60R18.

Is this a safe swap?

Diameter difference −0.79%: under 1%

By overall diameter alone, 255/60R18 is a near match for 225/75R17; 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: 225/75R17 (30.29 in) vs 255/60R18 (30.05 in)225/75R1730.29 in × 8.86 in255/60R1830.05 in × 10.04 in
Side profile and tread width, drawn to the same scale.
225/75R17 vs 255/60R18 differences
Measurement225/75R17255/60R18Difference% diff
Overall diameter30.29 in (769.3 mm)30.05 in (763.2 mm)−0.24 in (−6.1 mm)−0.79%
Sidewall height6.64 in (168.8 mm)6.02 in (153.0 mm)−0.62 in (−15.7 mm)−9.33%
Section width8.86 in (225.0 mm)10.04 in (255.0 mm)+1.18 in (+30.0 mm)+13.33%
Circumference95.15 in (2,416.8 mm)94.40 in (2,397.7 mm)−0.75 in (−19.2 mm)−0.79%
Revolutions per mile666671+5+0.80%
True speed with the speedometer calibrated for 225/75R17
IndicatedActual on 225/75R17Actual on 255/60R18Difference
30 mph30.0 mph29.8 mph−0.2 mph
60 mph60.0 mph59.5 mph−0.5 mph
75 mph75.0 mph74.4 mph−0.6 mph

Ride-height change: 255/60R18 lowers the vehicle by 0.12 in (3.0 mm) at the axle (half the −6.1 mm diameter difference).

255/60R18 is 0.24 in shorter than 225/75R17 and 30 mm wider, a 0.79% difference in overall diameter.

With the speedometer calibrated for 225/75R17, an indicated 60 mph is actually 59.5 mph on 255/60R18, and revolutions per mile change from 666 to 671.

255/60R18 mounts on a 18-inch wheel, a plus-1 fitment from the 17-inch wheel of 225/75R17.

Size pages

Other comparisons with 225/75R17

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