245/60R17 vs 265/50R18

265/50R18 is 0.14 in (3.6 mm) shorter than 245/60R17, a −0.50% diameter difference. With the speedometer set for 245/60R17, an indicated 60 mph is 59.7 mph on 265/50R18.

Is this a safe swap?

Diameter difference −0.50%: under 1%

By overall diameter alone, 265/50R18 is a near match for 245/60R17; 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.

245/60R17 vs 265/50R18 differences
Measurement	245/60R17	265/50R18	Difference	% diff
Overall diameter	28.57 in (725.8 mm)	28.43 in (722.2 mm)	−0.14 in (−3.6 mm)	−0.50%
Sidewall height	5.79 in (147.0 mm)	5.22 in (132.5 mm)	−0.57 in (−14.5 mm)	−9.86%
Section width	9.65 in (245.0 mm)	10.43 in (265.0 mm)	+0.79 in (+20.0 mm)	+8.16%
Circumference	89.77 in (2,280.2 mm)	89.33 in (2,268.9 mm)	−0.45 in (−11.3 mm)	−0.50%
Revolutions per mile	706	709	+4	+0.50%

True speed with the speedometer calibrated for 245/60R17
Indicated	Actual on 245/60R17	Actual on 265/50R18	Difference
30 mph	30.0 mph	29.9 mph	−0.1 mph
60 mph	60.0 mph	59.7 mph	−0.3 mph
75 mph	75.0 mph	74.6 mph	−0.4 mph

Ride-height change: 265/50R18 lowers the vehicle by 0.07 in (1.8 mm) at the axle (half the −3.6 mm diameter difference).

265/50R18 is 0.14 in shorter than 245/60R17 and 20 mm wider, a 0.50% difference in overall diameter.

With the speedometer calibrated for 245/60R17, an indicated 60 mph is actually 59.7 mph on 265/50R18, and revolutions per mile change from 706 to 709.

265/50R18 mounts on a 18-inch wheel, a plus-1 fitment from the 17-inch wheel of 245/60R17.

Size pages

Other comparisons with 245/60R17

Other comparisons with 265/50R18

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