185/60R15 vs 225/40R17

225/40R17 is 0.35 in (8.8 mm) taller than 185/60R15, a +1.46% diameter difference. With the speedometer set for 185/60R15, an indicated 60 mph is 60.9 mph on 225/40R17.

Is this a safe swap?

Diameter difference +1.46%: within the ±3% guideline

By overall diameter alone, 225/40R17 falls inside the ±3% range commonly used as a guideline when replacing 185/60R15. 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.

185/60R15 vs 225/40R17 differences
Measurement	185/60R15	225/40R17	Difference	% diff
Overall diameter	23.74 in (603.0 mm)	24.09 in (611.8 mm)	+0.35 in (+8.8 mm)	+1.46%
Sidewall height	4.37 in (111.0 mm)	3.54 in (90.0 mm)	−0.83 in (−21.0 mm)	−18.92%
Section width	7.28 in (185.0 mm)	8.86 in (225.0 mm)	+1.57 in (+40.0 mm)	+21.62%
Circumference	74.58 in (1,894.4 mm)	75.67 in (1,922.0 mm)	+1.09 in (+27.6 mm)	+1.46%
Revolutions per mile	850	837	−12	−1.44%

True speed with the speedometer calibrated for 185/60R15
Indicated	Actual on 185/60R15	Actual on 225/40R17	Difference
30 mph	30.0 mph	30.4 mph	+0.4 mph
60 mph	60.0 mph	60.9 mph	+0.9 mph
75 mph	75.0 mph	76.1 mph	+1.1 mph

Ride-height change: 225/40R17 raises the vehicle by 0.17 in (4.4 mm) at the axle (half the +8.8 mm diameter difference).

225/40R17 is 0.35 in taller than 185/60R15 and 40 mm wider, a 1.46% difference in overall diameter.

With the speedometer calibrated for 185/60R15, an indicated 60 mph is actually 60.9 mph on 225/40R17, and revolutions per mile change from 850 to 837.

225/40R17 mounts on a 17-inch wheel, a plus-2 fitment from the 15-inch wheel of 185/60R15.

Size pages

Other comparisons with 185/60R15

Other comparisons with 225/40R17

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