265/75R16 vs 275/65R18

275/65R18 is 0.43 in (10.8 mm) taller than 265/75R16, a +1.34% diameter difference. With the speedometer set for 265/75R16, an indicated 60 mph is 60.8 mph on 275/65R18.

Is this a safe swap?

Diameter difference +1.34%: within the ±3% guideline

By overall diameter alone, 275/65R18 falls inside the ±3% range commonly used as a guideline when replacing 265/75R16. 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.

265/75R16 vs 275/65R18 differences
Measurement	265/75R16	275/65R18	Difference	% diff
Overall diameter	31.65 in (803.9 mm)	32.07 in (814.7 mm)	+0.43 in (+10.8 mm)	+1.34%
Sidewall height	7.82 in (198.8 mm)	7.04 in (178.8 mm)	−0.79 in (−20.0 mm)	−10.06%
Section width	10.43 in (265.0 mm)	10.83 in (275.0 mm)	+0.39 in (+10.0 mm)	+3.77%
Circumference	99.43 in (2,525.5 mm)	100.77 in (2,559.5 mm)	+1.34 in (+33.9 mm)	+1.34%
Revolutions per mile	637	629	−8	−1.33%

True speed with the speedometer calibrated for 265/75R16
Indicated	Actual on 265/75R16	Actual on 275/65R18	Difference
30 mph	30.0 mph	30.4 mph	+0.4 mph
60 mph	60.0 mph	60.8 mph	+0.8 mph
75 mph	75.0 mph	76.0 mph	+1.0 mph

Ride-height change: 275/65R18 raises the vehicle by 0.21 in (5.4 mm) at the axle (half the +10.8 mm diameter difference).

275/65R18 is 0.43 in taller than 265/75R16 and 10 mm wider, a 1.34% difference in overall diameter.

With the speedometer calibrated for 265/75R16, an indicated 60 mph is actually 60.8 mph on 275/65R18, and revolutions per mile change from 637 to 629.

275/65R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 265/75R16.

Size pages

Other comparisons with 265/75R16

Other comparisons with 275/65R18

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