TireSizesFinder

235/60R16 vs 225/50R18

225/50R18 is 0.24 in (6.2 mm) shorter than 235/60R16, a −0.90% diameter difference. With the speedometer set for 235/60R16, an indicated 60 mph is 59.5 mph on 225/50R18.

Is this a safe swap?

Diameter difference −0.90%: under 1%

By overall diameter alone, 225/50R18 is a near match for 235/60R16; 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: 235/60R16 (27.10 in) vs 225/50R18 (26.86 in)235/60R1627.10 in × 9.25 in225/50R1826.86 in × 8.86 in
Side profile and tread width, drawn to the same scale.
235/60R16 vs 225/50R18 differences
Measurement235/60R16225/50R18Difference% diff
Overall diameter27.10 in (688.4 mm)26.86 in (682.2 mm)−0.24 in (−6.2 mm)−0.90%
Sidewall height5.55 in (141.0 mm)4.43 in (112.5 mm)−1.12 in (−28.5 mm)−20.21%
Section width9.25 in (235.0 mm)8.86 in (225.0 mm)−0.39 in (−10.0 mm)−4.26%
Circumference85.14 in (2,162.7 mm)84.38 in (2,143.2 mm)−0.77 in (−19.5 mm)−0.90%
Revolutions per mile744751+7+0.91%
True speed with the speedometer calibrated for 235/60R16
IndicatedActual on 235/60R16Actual on 225/50R18Difference
30 mph30.0 mph29.7 mph−0.3 mph
60 mph60.0 mph59.5 mph−0.5 mph
75 mph75.0 mph74.3 mph−0.7 mph

Ride-height change: 225/50R18 lowers the vehicle by 0.12 in (3.1 mm) at the axle (half the −6.2 mm diameter difference).

225/50R18 is 0.24 in shorter than 235/60R16 and 10 mm narrower, a 0.90% difference in overall diameter.

With the speedometer calibrated for 235/60R16, an indicated 60 mph is actually 59.5 mph on 225/50R18, and revolutions per mile change from 744 to 751.

225/50R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 235/60R16.

Size pages

Other comparisons with 235/60R16

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