265/65R17 vs 255/70R17

255/70R17 is 0.49 in (12.5 mm) taller than 265/65R17, a +1.61% diameter difference. With the speedometer set for 265/65R17, an indicated 60 mph is 61.0 mph on 255/70R17.

Is this a safe swap?

Diameter difference +1.61%: within the ±3% guideline

By overall diameter alone, 255/70R17 falls inside the ±3% range commonly used as a guideline when replacing 265/65R17. 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.

265/65R17 vs 255/70R17 differences
Measurement	265/65R17	255/70R17	Difference	% diff
Overall diameter	30.56 in (776.3 mm)	31.06 in (788.8 mm)	+0.49 in (+12.5 mm)	+1.61%
Sidewall height	6.78 in (172.3 mm)	7.03 in (178.5 mm)	+0.25 in (+6.3 mm)	+3.63%
Section width	10.43 in (265.0 mm)	10.04 in (255.0 mm)	−0.39 in (−10.0 mm)	−3.77%
Circumference	96.02 in (2,438.8 mm)	97.56 in (2,478.1 mm)	+1.55 in (+39.3 mm)	+1.61%
Revolutions per mile	660	649	−10	−1.58%

True speed with the speedometer calibrated for 265/65R17
Indicated	Actual on 265/65R17	Actual on 255/70R17	Difference
30 mph	30.0 mph	30.5 mph	+0.5 mph
60 mph	60.0 mph	61.0 mph	+1.0 mph
75 mph	75.0 mph	76.2 mph	+1.2 mph

Ride-height change: 255/70R17 raises the vehicle by 0.25 in (6.3 mm) at the axle (half the +12.5 mm diameter difference).

255/70R17 is 0.49 in taller than 265/65R17 and 10 mm narrower, a 1.61% difference in overall diameter.

With the speedometer calibrated for 265/65R17, an indicated 60 mph is actually 61.0 mph on 255/70R17, and revolutions per mile change from 660 to 649.

Both sizes mount on 17-inch wheels.

Size pages

Other comparisons with 265/65R17

Other comparisons with 255/70R17

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