255/70R15 vs 245/65R17

245/65R17 is 0.48 in (12.3 mm) taller than 255/70R15, a +1.67% diameter difference. With the speedometer set for 255/70R15, an indicated 60 mph is 61.0 mph on 245/65R17.

Is this a safe swap?

Diameter difference +1.67%: within the ±3% guideline

By overall diameter alone, 245/65R17 falls inside the ±3% range commonly used as a guideline when replacing 255/70R15. 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.

255/70R15 vs 245/65R17 differences
Measurement	255/70R15	245/65R17	Difference	% diff
Overall diameter	29.06 in (738.0 mm)	29.54 in (750.3 mm)	+0.48 in (+12.3 mm)	+1.67%
Sidewall height	7.03 in (178.5 mm)	6.27 in (159.3 mm)	−0.76 in (−19.2 mm)	−10.78%
Section width	10.04 in (255.0 mm)	9.65 in (245.0 mm)	−0.39 in (−10.0 mm)	−3.92%
Circumference	91.28 in (2,318.5 mm)	92.80 in (2,357.1 mm)	+1.52 in (+38.6 mm)	+1.67%
Revolutions per mile	694	683	−11	−1.64%

True speed with the speedometer calibrated for 255/70R15
Indicated	Actual on 255/70R15	Actual on 245/65R17	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	76.3 mph	+1.3 mph

Ride-height change: 245/65R17 raises the vehicle by 0.24 in (6.1 mm) at the axle (half the +12.3 mm diameter difference).

245/65R17 is 0.48 in taller than 255/70R15 and 10 mm narrower, a 1.67% difference in overall diameter.

With the speedometer calibrated for 255/70R15, an indicated 60 mph is actually 61.0 mph on 245/65R17, and revolutions per mile change from 694 to 683.

245/65R17 mounts on a 17-inch wheel, a plus-2 fitment from the 15-inch wheel of 255/70R15.

Size pages

Other comparisons with 255/70R15

Other comparisons with 245/65R17

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