Tire Size Box

185/55R17 vs 205/55R17

205/55R17 compared with 185/55R17

+3.5% diameter, +0.8" width

205/55R17 is 25.88" tall vs 25.01". More than the 3% rule of thumb, so check carefully before switching.

25.0"17" rim4.0"7.3" wide
185/55R17 (solid) compared with 205/55R17 (dashed outline), drawn to scale

With 205/55R17 tires, when your speedometer says 60 mph you are really going

62.1 mph

205/55R17 is +0.87 inches (+3.5%) in overall diameter. That is more than the 3% most shops and makers recommend.

185/55R17205/55R17Difference%
Overall diameter25.01"25.88"+0.87"+3.5%
Section width7.28"8.07"+0.79"+10.8%
Sidewall height4.01"4.44"+0.43"+10.8%
Circumference78.58"81.30"+2.72"+3.5%
Revolutions per mile806.3779.4−27.0−3.3%

Speedometer difference

If your vehicle came with 185/55R17 and you fit 205/55R17, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.7 mph+0.7 mph
30 mph31.0 mph+1.0 mph
40 mph41.4 mph+1.4 mph
50 mph51.7 mph+1.7 mph
60 mph62.1 mph+2.1 mph
65 mph67.3 mph+2.3 mph
70 mph72.4 mph+2.4 mph
75 mph77.6 mph+2.6 mph
80 mph82.8 mph+2.8 mph

Each size on its own

Questions

Which is bigger, 185/55R17 or 205/55R17?
205/55R17 is taller by 0.87 inches (25.88" vs 25.01"). 205/55R17 is wider by 0.79 inches.
Can I replace 185/55R17 with 205/55R17?
It is not recommended without checking carefully. The diameter difference is +3.5%, more than the 3% most shops and makers allow. It will throw off the speedometer and may affect ABS, stability control and clearance.
How much will 205/55R17 change my speedometer?
When your speedometer reads 60 mph with 205/55R17 fitted (calibrated for 185/55R17), your real speed is 62.1 mph. Your odometer will under-count miles by about 3.5%.
Will 205/55R17 lift my vehicle?
Ride height changes by half the diameter difference: +0.43 inches of ground clearance at the axle.

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