TireSizesFinder

235/75R16 vs 275/55R18

275/55R18 is 0.03 in (0.8 mm) taller than 235/75R16, a +0.11% diameter difference. With the speedometer set for 235/75R16, an indicated 60 mph is 60.1 mph on 275/55R18.

Is this a safe swap?

Diameter difference +0.11%: under 1%

By overall diameter alone, 275/55R18 is a near match for 235/75R16; 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: 235/75R16 (29.88 in) vs 275/55R18 (29.91 in)235/75R1629.88 in × 9.25 in275/55R1829.91 in × 10.83 in
Side profile and tread width, drawn to the same scale.
235/75R16 vs 275/55R18 differences
Measurement235/75R16275/55R18Difference% diff
Overall diameter29.88 in (758.9 mm)29.91 in (759.7 mm)+0.03 in (+0.8 mm)+0.11%
Sidewall height6.94 in (176.3 mm)5.95 in (151.3 mm)−0.98 in (−25.0 mm)−14.18%
Section width9.25 in (235.0 mm)10.83 in (275.0 mm)+1.57 in (+40.0 mm)+17.02%
Circumference93.86 in (2,384.2 mm)93.96 in (2,386.7 mm)+0.10 in (+2.5 mm)+0.11%
Revolutions per mile675674−1−0.11%
True speed with the speedometer calibrated for 235/75R16
IndicatedActual on 235/75R16Actual on 275/55R18Difference
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: 275/55R18 raises the vehicle by 0.02 in (0.4 mm) at the axle (half the +0.8 mm diameter difference).

275/55R18 is 0.03 in taller than 235/75R16 and 40 mm wider, a 0.11% difference in overall diameter.

With the speedometer calibrated for 235/75R16, an indicated 60 mph is actually 60.1 mph on 275/55R18, and revolutions per mile change from 675 to 674.

275/55R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 235/75R16.

Size pages

Other comparisons with 235/75R16

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