205/75R15 vs 245/50R17

245/50R17 is 0.46 in (11.7 mm) shorter than 205/75R15, a −1.70% diameter difference. With the speedometer set for 205/75R15, an indicated 60 mph is 59.0 mph on 245/50R17.

Is this a safe swap?

Diameter difference −1.70%: within the ±3% guideline

By overall diameter alone, 245/50R17 falls inside the ±3% range commonly used as a guideline when replacing 205/75R15. 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.

205/75R15 vs 245/50R17 differences
Measurement	205/75R15	245/50R17	Difference	% diff
Overall diameter	27.11 in (688.5 mm)	26.65 in (676.8 mm)	−0.46 in (−11.7 mm)	−1.70%
Sidewall height	6.05 in (153.8 mm)	4.82 in (122.5 mm)	−1.23 in (−31.2 mm)	−20.33%
Section width	8.07 in (205.0 mm)	9.65 in (245.0 mm)	+1.57 in (+40.0 mm)	+19.51%
Circumference	85.16 in (2,163.0 mm)	83.71 in (2,126.2 mm)	−1.45 in (−36.8 mm)	−1.70%
Revolutions per mile	744	757	+13	+1.73%

True speed with the speedometer calibrated for 205/75R15
Indicated	Actual on 205/75R15	Actual on 245/50R17	Difference
30 mph	30.0 mph	29.5 mph	−0.5 mph
60 mph	60.0 mph	59.0 mph	−1.0 mph
75 mph	75.0 mph	73.7 mph	−1.3 mph

Ride-height change: 245/50R17 lowers the vehicle by 0.23 in (5.9 mm) at the axle (half the −11.7 mm diameter difference).

245/50R17 is 0.46 in shorter than 205/75R15 and 40 mm wider, a 1.70% difference in overall diameter.

With the speedometer calibrated for 205/75R15, an indicated 60 mph is actually 59.0 mph on 245/50R17, and revolutions per mile change from 744 to 757.

245/50R17 mounts on a 17-inch wheel, a plus-2 fitment from the 15-inch wheel of 205/75R15.

Size pages

Other comparisons with 205/75R15

Other comparisons with 245/50R17

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