TireSizesFinder

185/65R15 vs 205/45R17

205/45R17 is 0.20 in (5.2 mm) shorter than 185/65R15, a −0.84% diameter difference. With the speedometer set for 185/65R15, an indicated 60 mph is 59.5 mph on 205/45R17.

Is this a safe swap?

Diameter difference −0.84%: under 1%

By overall diameter alone, 205/45R17 is a near match for 185/65R15; the speedometer changes by less than 1%. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 185/65R15 (24.47 in) vs 205/45R17 (24.26 in)185/65R1524.47 in × 7.28 in205/45R1724.26 in × 8.07 in
Side profile and tread width, drawn to the same scale.
185/65R15 vs 205/45R17 differences
Measurement185/65R15205/45R17Difference% diff
Overall diameter24.47 in (621.5 mm)24.26 in (616.3 mm)−0.20 in (−5.2 mm)−0.84%
Sidewall height4.73 in (120.3 mm)3.63 in (92.3 mm)−1.10 in (−28.0 mm)−23.28%
Section width7.28 in (185.0 mm)8.07 in (205.0 mm)+0.79 in (+20.0 mm)+10.81%
Circumference76.87 in (1,952.5 mm)76.23 in (1,936.2 mm)−0.64 in (−16.3 mm)−0.84%
Revolutions per mile824831+7+0.84%
True speed with the speedometer calibrated for 185/65R15
IndicatedActual on 185/65R15Actual on 205/45R17Difference
30 mph30.0 mph29.7 mph−0.3 mph
60 mph60.0 mph59.5 mph−0.5 mph
75 mph75.0 mph74.4 mph−0.6 mph

Ride-height change: 205/45R17 lowers the vehicle by 0.10 in (2.6 mm) at the axle (half the −5.2 mm diameter difference).

205/45R17 is 0.20 in shorter than 185/65R15 and 20 mm wider, a 0.84% difference in overall diameter.

With the speedometer calibrated for 185/65R15, an indicated 60 mph is actually 59.5 mph on 205/45R17, and revolutions per mile change from 824 to 831.

205/45R17 mounts on a 17-inch wheel, a plus-2 fitment from the 15-inch wheel of 185/65R15.

Size pages

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Source: Calculated from standard tire geometry formulas. Verified . How these numbers are calculated.