225/65R16 vs 265/45R18

265/45R18 is 0.13 in (3.2 mm) shorter than 225/65R16, a −0.46% diameter difference. With the speedometer set for 225/65R16, an indicated 60 mph is 59.7 mph on 265/45R18.

Is this a safe swap?

Diameter difference −0.46%: under 1%

By overall diameter alone, 265/45R18 is a near match for 225/65R16; 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.

225/65R16 vs 265/45R18 differences
Measurement	225/65R16	265/45R18	Difference	% diff
Overall diameter	27.52 in (698.9 mm)	27.39 in (695.7 mm)	−0.13 in (−3.2 mm)	−0.46%
Sidewall height	5.76 in (146.3 mm)	4.69 in (119.3 mm)	−1.06 in (−27.0 mm)	−18.46%
Section width	8.86 in (225.0 mm)	10.43 in (265.0 mm)	+1.57 in (+40.0 mm)	+17.78%
Circumference	86.44 in (2,195.7 mm)	86.05 in (2,185.6 mm)	−0.40 in (−10.1 mm)	−0.46%
Revolutions per mile	733	736	+3	+0.46%

True speed with the speedometer calibrated for 225/65R16
Indicated	Actual on 225/65R16	Actual on 265/45R18	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	74.7 mph	−0.3 mph

Ride-height change: 265/45R18 lowers the vehicle by 0.06 in (1.6 mm) at the axle (half the −3.2 mm diameter difference).

265/45R18 is 0.13 in shorter than 225/65R16 and 40 mm wider, a 0.46% difference in overall diameter.

With the speedometer calibrated for 225/65R16, an indicated 60 mph is actually 59.7 mph on 265/45R18, and revolutions per mile change from 733 to 736.

265/45R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 225/65R16.

Size pages

Other comparisons with 225/65R16

Other comparisons with 265/45R18

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