225/60R16 vs 215/50R18

215/50R18 is 0.17 in (4.2 mm) shorter than 225/60R16, a −0.62% diameter difference. With the speedometer set for 225/60R16, an indicated 60 mph is 59.6 mph on 215/50R18.

Is this a safe swap?

Diameter difference −0.62%: under 1%

By overall diameter alone, 215/50R18 is a near match for 225/60R16; 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: 225/60R16 (26.63 in) vs 215/50R18 (26.46 in)225/60R1626.63 in × 8.86 in215/50R1826.46 in × 8.46 in
Side profile and tread width, drawn to the same scale.
225/60R16 vs 215/50R18 differences
Measurement225/60R16215/50R18Difference% diff
Overall diameter26.63 in (676.4 mm)26.46 in (672.2 mm)−0.17 in (−4.2 mm)−0.62%
Sidewall height5.31 in (135.0 mm)4.23 in (107.5 mm)−1.08 in (−27.5 mm)−20.37%
Section width8.86 in (225.0 mm)8.46 in (215.0 mm)−0.39 in (−10.0 mm)−4.44%
Circumference83.66 in (2,125.0 mm)83.14 in (2,111.8 mm)−0.52 in (−13.2 mm)−0.62%
Revolutions per mile757762+5+0.62%
True speed with the speedometer calibrated for 225/60R16
IndicatedActual on 225/60R16Actual on 215/50R18Difference
30 mph30.0 mph29.8 mph−0.2 mph
60 mph60.0 mph59.6 mph−0.4 mph
75 mph75.0 mph74.5 mph−0.5 mph

Ride-height change: 215/50R18 lowers the vehicle by 0.08 in (2.1 mm) at the axle (half the −4.2 mm diameter difference).

215/50R18 is 0.17 in shorter than 225/60R16 and 10 mm narrower, a 0.62% difference in overall diameter.

With the speedometer calibrated for 225/60R16, an indicated 60 mph is actually 59.6 mph on 215/50R18, and revolutions per mile change from 757 to 762.

215/50R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 225/60R16.

Size pages

Other comparisons with 225/60R16

Other comparisons with 215/50R18

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