205/75R16 vs 265/50R18

265/50R18 is 0.33 in (8.3 mm) taller than 205/75R16, a +1.16% diameter difference. With the speedometer set for 205/75R16, an indicated 60 mph is 60.7 mph on 265/50R18.

Is this a safe swap?

Diameter difference +1.16%: within the ±3% guideline

By overall diameter alone, 265/50R18 falls inside the ±3% range commonly used as a guideline when replacing 205/75R16. 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.

205/75R16 vs 265/50R18 differences
Measurement	205/75R16	265/50R18	Difference	% diff
Overall diameter	28.11 in (713.9 mm)	28.43 in (722.2 mm)	+0.33 in (+8.3 mm)	+1.16%
Sidewall height	6.05 in (153.8 mm)	5.22 in (132.5 mm)	−0.84 in (−21.2 mm)	−13.82%
Section width	8.07 in (205.0 mm)	10.43 in (265.0 mm)	+2.36 in (+60.0 mm)	+29.27%
Circumference	88.30 in (2,242.8 mm)	89.33 in (2,268.9 mm)	+1.03 in (+26.1 mm)	+1.16%
Revolutions per mile	718	709	−8	−1.15%

True speed with the speedometer calibrated for 205/75R16
Indicated	Actual on 205/75R16	Actual on 265/50R18	Difference
30 mph	30.0 mph	30.3 mph	+0.3 mph
60 mph	60.0 mph	60.7 mph	+0.7 mph
75 mph	75.0 mph	75.9 mph	+0.9 mph

Ride-height change: 265/50R18 raises the vehicle by 0.16 in (4.2 mm) at the axle (half the +8.3 mm diameter difference).

265/50R18 is 0.33 in taller than 205/75R16 and 60 mm wider, a 1.16% difference in overall diameter.

With the speedometer calibrated for 205/75R16, an indicated 60 mph is actually 60.7 mph on 265/50R18, and revolutions per mile change from 718 to 709.

265/50R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 205/75R16.

Size pages

Other comparisons with 205/75R16

Other comparisons with 265/50R18

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