215/75R16 vs 265/50R18

265/50R18 is 0.26 in (6.7 mm) shorter than 215/75R16, a −0.92% diameter difference. With the speedometer set for 215/75R16, an indicated 60 mph is 59.4 mph on 265/50R18.

Is this a safe swap?

Diameter difference −0.92%: under 1%

By overall diameter alone, 265/50R18 is a near match for 215/75R16; the speedometer changes by less than 1%. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

Side profile and tread width, drawn to the same scale.

215/75R16 vs 265/50R18 differences
Measurement	215/75R16	265/50R18	Difference	% diff
Overall diameter	28.70 in (728.9 mm)	28.43 in (722.2 mm)	−0.26 in (−6.7 mm)	−0.92%
Sidewall height	6.35 in (161.3 mm)	5.22 in (132.5 mm)	−1.13 in (−28.7 mm)	−17.83%
Section width	8.46 in (215.0 mm)	10.43 in (265.0 mm)	+1.97 in (+50.0 mm)	+23.26%
Circumference	90.15 in (2,289.9 mm)	89.33 in (2,268.9 mm)	−0.83 in (−21.0 mm)	−0.92%
Revolutions per mile	703	709	+7	+0.93%

True speed with the speedometer calibrated for 215/75R16
Indicated	Actual on 215/75R16	Actual on 265/50R18	Difference
30 mph	30.0 mph	29.7 mph	−0.3 mph
60 mph	60.0 mph	59.4 mph	−0.6 mph
75 mph	75.0 mph	74.3 mph	−0.7 mph

Ride-height change: 265/50R18 lowers the vehicle by 0.13 in (3.3 mm) at the axle (half the −6.7 mm diameter difference).

265/50R18 is 0.26 in shorter than 215/75R16 and 50 mm wider, a 0.92% difference in overall diameter.

With the speedometer calibrated for 215/75R16, an indicated 60 mph is actually 59.4 mph on 265/50R18, and revolutions per mile change from 703 to 709.

265/50R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 215/75R16.

Size pages

Other comparisons with 215/75R16

Other comparisons with 265/50R18

Source: Calculated from standard tire geometry formulas. Verified 2026-09-27. How these numbers are calculated.