TireSizesFinder

185/55R16 vs 205/45R17

205/45R17 is 0.25 in (6.4 mm) taller than 185/55R16, a +1.05% diameter difference. With the speedometer set for 185/55R16, an indicated 60 mph is 60.6 mph on 205/45R17.

Is this a safe swap?

Diameter difference +1.05%: within the ±3% guideline

By overall diameter alone, 205/45R17 falls inside the ±3% range commonly used as a guideline when replacing 185/55R16. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 185/55R16 (24.01 in) vs 205/45R17 (24.26 in)185/55R1624.01 in × 7.28 in205/45R1724.26 in × 8.07 in
Side profile and tread width, drawn to the same scale.
185/55R16 vs 205/45R17 differences
Measurement185/55R16205/45R17Difference% diff
Overall diameter24.01 in (609.9 mm)24.26 in (616.3 mm)+0.25 in (+6.4 mm)+1.05%
Sidewall height4.01 in (101.8 mm)3.63 in (92.3 mm)−0.37 in (−9.5 mm)−9.34%
Section width7.28 in (185.0 mm)8.07 in (205.0 mm)+0.79 in (+20.0 mm)+10.81%
Circumference75.44 in (1,916.1 mm)76.23 in (1,936.2 mm)+0.79 in (+20.1 mm)+1.05%
Revolutions per mile840831−9−1.04%
True speed with the speedometer calibrated for 185/55R16
IndicatedActual on 185/55R16Actual on 205/45R17Difference
30 mph30.0 mph30.3 mph+0.3 mph
60 mph60.0 mph60.6 mph+0.6 mph
75 mph75.0 mph75.8 mph+0.8 mph

Ride-height change: 205/45R17 raises the vehicle by 0.13 in (3.2 mm) at the axle (half the +6.4 mm diameter difference).

205/45R17 is 0.25 in taller than 185/55R16 and 20 mm wider, a 1.05% difference in overall diameter.

With the speedometer calibrated for 185/55R16, an indicated 60 mph is actually 60.6 mph on 205/45R17, and revolutions per mile change from 840 to 831.

205/45R17 mounts on a 17-inch wheel, a plus-1 fitment from the 16-inch wheel of 185/55R16.

Size pages

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