245/65R16 vs 265/50R18

265/50R18 is 0.11 in (2.7 mm) shorter than 245/65R16, a −0.37% diameter difference. With the speedometer set for 245/65R16, an indicated 60 mph is 59.8 mph on 265/50R18.

Is this a safe swap?

Diameter difference −0.37%: under 1%

By overall diameter alone, 265/50R18 is a near match for 245/65R16; the speedometer changes by less than 1%. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

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

245/65R16 vs 265/50R18 differences
Measurement	245/65R16	265/50R18	Difference	% diff
Overall diameter	28.54 in (724.9 mm)	28.43 in (722.2 mm)	−0.11 in (−2.7 mm)	−0.37%
Sidewall height	6.27 in (159.3 mm)	5.22 in (132.5 mm)	−1.05 in (−26.7 mm)	−16.80%
Section width	9.65 in (245.0 mm)	10.43 in (265.0 mm)	+0.79 in (+20.0 mm)	+8.16%
Circumference	89.66 in (2,277.3 mm)	89.33 in (2,268.9 mm)	−0.33 in (−8.5 mm)	−0.37%
Revolutions per mile	707	709	+3	+0.37%

True speed with the speedometer calibrated for 245/65R16
Indicated	Actual on 245/65R16	Actual on 265/50R18	Difference
30 mph	30.0 mph	29.9 mph	−0.1 mph
60 mph	60.0 mph	59.8 mph	−0.2 mph
75 mph	75.0 mph	74.7 mph	−0.3 mph

Ride-height change: 265/50R18 lowers the vehicle by 0.05 in (1.3 mm) at the axle (half the −2.7 mm diameter difference).

265/50R18 is 0.11 in shorter than 245/65R16 and 20 mm wider, a 0.37% difference in overall diameter.

With the speedometer calibrated for 245/65R16, an indicated 60 mph is actually 59.8 mph on 265/50R18, and revolutions per mile change from 707 to 709.

265/50R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 245/65R16.

Size pages

Other comparisons with 245/65R16

Other comparisons with 265/50R18

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