TireSizesFinder

215/65R16 vs 255/45R18

255/45R18 is 0.03 in (0.8 mm) taller than 215/65R16, a +0.12% diameter difference. With the speedometer set for 215/65R16, an indicated 60 mph is 60.1 mph on 255/45R18.

Is this a safe swap?

Diameter difference +0.12%: under 1%

By overall diameter alone, 255/45R18 is a near match for 215/65R16; 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: 215/65R16 (27.00 in) vs 255/45R18 (27.04 in)215/65R1627.00 in × 8.46 in255/45R1827.04 in × 10.04 in
Side profile and tread width, drawn to the same scale.
215/65R16 vs 255/45R18 differences
Measurement215/65R16255/45R18Difference% diff
Overall diameter27.00 in (685.9 mm)27.04 in (686.7 mm)+0.03 in (+0.8 mm)+0.12%
Sidewall height5.50 in (139.8 mm)4.52 in (114.8 mm)−0.98 in (−25.0 mm)−17.89%
Section width8.46 in (215.0 mm)10.04 in (255.0 mm)+1.57 in (+40.0 mm)+18.60%
Circumference84.84 in (2,154.8 mm)84.93 in (2,157.3 mm)+0.10 in (+2.5 mm)+0.12%
Revolutions per mile747746−1−0.12%
True speed with the speedometer calibrated for 215/65R16
IndicatedActual on 215/65R16Actual on 255/45R18Difference
30 mph30.0 mph30.0 mph0.0 mph
60 mph60.0 mph60.1 mph+0.1 mph
75 mph75.0 mph75.1 mph+0.1 mph

Ride-height change: 255/45R18 raises the vehicle by 0.02 in (0.4 mm) at the axle (half the +0.8 mm diameter difference).

255/45R18 is 0.03 in taller than 215/65R16 and 40 mm wider, a 0.12% difference in overall diameter.

With the speedometer calibrated for 215/65R16, an indicated 60 mph is actually 60.1 mph on 255/45R18, and revolutions per mile change from 747 to 746.

255/45R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 215/65R16.

Size pages

Other comparisons with 215/65R16

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