265/75R15 vs 255/70R17

255/70R17 is 0.41 in (10.3 mm) taller than 265/75R15, a +1.32% diameter difference. With the speedometer set for 265/75R15, an indicated 60 mph is 60.8 mph on 255/70R17.

Is this a safe swap?

Diameter difference +1.32%: within the ±3% guideline

By overall diameter alone, 255/70R17 falls inside the ±3% range commonly used as a guideline when replacing 265/75R15. 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.

265/75R15 vs 255/70R17 differences
Measurement	265/75R15	255/70R17	Difference	% diff
Overall diameter	30.65 in (778.5 mm)	31.06 in (788.8 mm)	+0.41 in (+10.3 mm)	+1.32%
Sidewall height	7.82 in (198.8 mm)	7.03 in (178.5 mm)	−0.80 in (−20.2 mm)	−10.19%
Section width	10.43 in (265.0 mm)	10.04 in (255.0 mm)	−0.39 in (−10.0 mm)	−3.77%
Circumference	96.29 in (2,445.7 mm)	97.56 in (2,478.1 mm)	+1.27 in (+32.4 mm)	+1.32%
Revolutions per mile	658	649	−9	−1.31%

True speed with the speedometer calibrated for 265/75R15
Indicated	Actual on 265/75R15	Actual on 255/70R17	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: 255/70R17 raises the vehicle by 0.20 in (5.1 mm) at the axle (half the +10.3 mm diameter difference).

255/70R17 is 0.41 in taller than 265/75R15 and 10 mm narrower, a 1.32% difference in overall diameter.

With the speedometer calibrated for 265/75R15, an indicated 60 mph is actually 60.8 mph on 255/70R17, and revolutions per mile change from 658 to 649.

255/70R17 mounts on a 17-inch wheel, a plus-2 fitment from the 15-inch wheel of 265/75R15.

Size pages

Other comparisons with 265/75R15

Other comparisons with 255/70R17

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