205/70R15 vs 245/50R17

245/50R17 is 0.35 in (8.8 mm) taller than 205/70R15, a +1.32% diameter difference. With the speedometer set for 205/70R15, an indicated 60 mph is 60.8 mph on 245/50R17.

Is this a safe swap?

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

By overall diameter alone, 245/50R17 falls inside the ±3% range commonly used as a guideline when replacing 205/70R15. 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.

205/70R15 vs 245/50R17 differences
Measurement	205/70R15	245/50R17	Difference	% diff
Overall diameter	26.30 in (668.0 mm)	26.65 in (676.8 mm)	+0.35 in (+8.8 mm)	+1.32%
Sidewall height	5.65 in (143.5 mm)	4.82 in (122.5 mm)	−0.83 in (−21.0 mm)	−14.63%
Section width	8.07 in (205.0 mm)	9.65 in (245.0 mm)	+1.57 in (+40.0 mm)	+19.51%
Circumference	82.62 in (2,098.6 mm)	83.71 in (2,126.2 mm)	+1.09 in (+27.6 mm)	+1.32%
Revolutions per mile	767	757	−10	−1.30%

True speed with the speedometer calibrated for 205/70R15
Indicated	Actual on 205/70R15	Actual on 245/50R17	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: 245/50R17 raises the vehicle by 0.17 in (4.4 mm) at the axle (half the +8.8 mm diameter difference).

245/50R17 is 0.35 in taller than 205/70R15 and 40 mm wider, a 1.32% difference in overall diameter.

With the speedometer calibrated for 205/70R15, an indicated 60 mph is actually 60.8 mph on 245/50R17, and revolutions per mile change from 767 to 757.

245/50R17 mounts on a 17-inch wheel, a plus-2 fitment from the 15-inch wheel of 205/70R15.

Size pages

Other comparisons with 205/70R15

Other comparisons with 245/50R17

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