265/45R18 vs 285/45R18

285/45R18 is 0.71 in (18.0 mm) taller than 265/45R18, a +2.59% diameter difference. With the speedometer set for 265/45R18, an indicated 60 mph is 61.6 mph on 285/45R18.

Is this a safe swap?

Diameter difference +2.59%: within the ±3% guideline

By overall diameter alone, 285/45R18 falls inside the ±3% range commonly used as a guideline when replacing 265/45R18. 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.

265/45R18 vs 285/45R18 differences
Measurement	265/45R18	285/45R18	Difference	% diff
Overall diameter	27.39 in (695.7 mm)	28.10 in (713.7 mm)	+0.71 in (+18.0 mm)	+2.59%
Sidewall height	4.69 in (119.3 mm)	5.05 in (128.3 mm)	+0.35 in (+9.0 mm)	+7.55%
Section width	10.43 in (265.0 mm)	11.22 in (285.0 mm)	+0.79 in (+20.0 mm)	+7.55%
Circumference	86.05 in (2,185.6 mm)	88.27 in (2,242.2 mm)	+2.23 in (+56.5 mm)	+2.59%
Revolutions per mile	736	718	−19	−2.52%

True speed with the speedometer calibrated for 265/45R18
Indicated	Actual on 265/45R18	Actual on 285/45R18	Difference
30 mph	30.0 mph	30.8 mph	+0.8 mph
60 mph	60.0 mph	61.6 mph	+1.6 mph
75 mph	75.0 mph	76.9 mph	+1.9 mph

Ride-height change: 285/45R18 raises the vehicle by 0.35 in (9.0 mm) at the axle (half the +18.0 mm diameter difference).

285/45R18 is 0.71 in taller than 265/45R18 and 20 mm wider, a 2.59% difference in overall diameter.

With the speedometer calibrated for 265/45R18, an indicated 60 mph is actually 61.6 mph on 285/45R18, and revolutions per mile change from 736 to 718.

Both sizes mount on 18-inch wheels.

Size pages

Other comparisons with 265/45R18

Other comparisons with 285/45R18

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