245/75R15 vs 255/60R17

255/60R17 is 0.42 in (10.7 mm) shorter than 245/75R15, a −1.43% diameter difference. With the speedometer set for 245/75R15, an indicated 60 mph is 59.1 mph on 255/60R17.

Is this a safe swap?

Diameter difference −1.43%: within the ±3% guideline

By overall diameter alone, 255/60R17 falls inside the ±3% range commonly used as a guideline when replacing 245/75R15. 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.

245/75R15 vs 255/60R17 differences
Measurement	245/75R15	255/60R17	Difference	% diff
Overall diameter	29.47 in (748.5 mm)	29.05 in (737.8 mm)	−0.42 in (−10.7 mm)	−1.43%
Sidewall height	7.23 in (183.8 mm)	6.02 in (153.0 mm)	−1.21 in (−30.7 mm)	−16.73%
Section width	9.65 in (245.0 mm)	10.04 in (255.0 mm)	+0.39 in (+10.0 mm)	+4.08%
Circumference	92.58 in (2,351.5 mm)	91.25 in (2,317.9 mm)	−1.32 in (−33.6 mm)	−1.43%
Revolutions per mile	684	694	+10	+1.45%

True speed with the speedometer calibrated for 245/75R15
Indicated	Actual on 245/75R15	Actual on 255/60R17	Difference
30 mph	30.0 mph	29.6 mph	−0.4 mph
60 mph	60.0 mph	59.1 mph	−0.9 mph
75 mph	75.0 mph	73.9 mph	−1.1 mph

Ride-height change: 255/60R17 lowers the vehicle by 0.21 in (5.4 mm) at the axle (half the −10.7 mm diameter difference).

255/60R17 is 0.42 in shorter than 245/75R15 and 10 mm wider, a 1.43% difference in overall diameter.

With the speedometer calibrated for 245/75R15, an indicated 60 mph is actually 59.1 mph on 255/60R17, and revolutions per mile change from 684 to 694.

255/60R17 mounts on a 17-inch wheel, a plus-2 fitment from the 15-inch wheel of 245/75R15.

Size pages

Other comparisons with 245/75R15

Other comparisons with 255/60R17

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