Tire Size Box

185/85R13 vs 205/85R13

205/85R13 compared with 185/85R13

+5.3% diameter, +0.8" width

205/85R13 is 26.72" tall vs 25.38". More than the 3% rule of thumb, so check carefully before switching.

25.4"13" rim6.2"7.3" wide
185/85R13 (solid) compared with 205/85R13 (dashed outline), drawn to scale

With 205/85R13 tires, when your speedometer says 60 mph you are really going

63.2 mph

205/85R13 is +1.34 inches (+5.3%) in overall diameter. That is more than the 3% most shops and makers recommend.

185/85R13205/85R13Difference%
Overall diameter25.38"26.72"+1.34"+5.3%
Section width7.28"8.07"+0.79"+10.8%
Sidewall height6.19"6.86"+0.67"+10.8%
Circumference79.74"83.94"+4.21"+5.3%
Revolutions per mile794.6754.8−39.8−5.0%

Speedometer difference

If your vehicle came with 185/85R13 and you fit 205/85R13, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.1 mph+1.1 mph
30 mph31.6 mph+1.6 mph
40 mph42.1 mph+2.1 mph
50 mph52.6 mph+2.6 mph
60 mph63.2 mph+3.2 mph
65 mph68.4 mph+3.4 mph
70 mph73.7 mph+3.7 mph
75 mph79.0 mph+4.0 mph
80 mph84.2 mph+4.2 mph

Each size on its own

Questions

Which is bigger, 185/85R13 or 205/85R13?
205/85R13 is taller by 1.34 inches (26.72" vs 25.38"). 205/85R13 is wider by 0.79 inches.
Can I replace 185/85R13 with 205/85R13?
It is not recommended without checking carefully. The diameter difference is +5.3%, 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 205/85R13 change my speedometer?
When your speedometer reads 60 mph with 205/85R13 fitted (calibrated for 185/85R13), your real speed is 63.2 mph. Your odometer will under-count miles by about 5.3%.
Will 205/85R13 lift my vehicle?
Ride height changes by half the diameter difference: +0.67 inches of ground clearance at the axle.

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