Tire Size Box

185/45R16 vs 205/45R16

205/45R16 compared with 185/45R16

+3.1% diameter, +0.8" width

205/45R16 is 23.26" tall vs 22.56". More than the 3% rule of thumb, so check carefully before switching.

22.6"16" rim3.3"7.3" wide
185/45R16 (solid) compared with 205/45R16 (dashed outline), drawn to scale

With 205/45R16 tires, when your speedometer says 60 mph you are really going

61.9 mph

205/45R16 is +0.71 inches (+3.1%) in overall diameter. That is more than the 3% most shops and makers recommend.

185/45R16205/45R16Difference%
Overall diameter22.56"23.26"+0.71"+3.1%
Section width7.28"8.07"+0.79"+10.8%
Sidewall height3.28"3.63"+0.35"+10.8%
Circumference70.86"73.09"+2.23"+3.1%
Revolutions per mile894.2866.9−27.2−3.0%

Speedometer difference

If your vehicle came with 185/45R16 and you fit 205/45R16, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.6 mph+0.6 mph
30 mph30.9 mph+0.9 mph
40 mph41.3 mph+1.3 mph
50 mph51.6 mph+1.6 mph
60 mph61.9 mph+1.9 mph
65 mph67.0 mph+2.0 mph
70 mph72.2 mph+2.2 mph
75 mph77.4 mph+2.4 mph
80 mph82.5 mph+2.5 mph

Each size on its own

Questions

Which is bigger, 185/45R16 or 205/45R16?
205/45R16 is taller by 0.71 inches (23.26" vs 22.56"). 205/45R16 is wider by 0.79 inches.
Can I replace 185/45R16 with 205/45R16?
It is not recommended without checking carefully. The diameter difference is +3.1%, 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 205/45R16 change my speedometer?
When your speedometer reads 60 mph with 205/45R16 fitted (calibrated for 185/45R16), your real speed is 61.9 mph. Your odometer will under-count miles by about 3.1%.
Will 205/45R16 lift my vehicle?
Ride height changes by half the diameter difference: +0.35 inches of ground clearance at the axle.

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