Tire Size Box

185/75R13 vs 185/85R13

185/85R13 compared with 185/75R13

+6.1% diameter, 0.0" width

185/85R13 is 25.38" tall vs 23.93". More than the 3% rule of thumb, so check carefully before switching.

23.9"13" rim5.5"7.3" wide
185/75R13 (solid) compared with 185/85R13 (dashed outline), drawn to scale

With 185/85R13 tires, when your speedometer says 60 mph you are really going

63.7 mph

185/85R13 is +1.46 inches (+6.1%) in overall diameter. That is more than the 3% most shops and makers recommend.

185/75R13185/85R13Difference%
Overall diameter23.93"25.38"+1.46"+6.1%
Section width7.28"7.28"0.00"0.0%
Sidewall height5.46"6.19"+0.73"+13.3%
Circumference75.16"79.74"+4.58"+6.1%
Revolutions per mile843.0794.6−48.4−5.7%

Speedometer difference

If your vehicle came with 185/75R13 and you fit 185/85R13, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.2 mph+1.2 mph
30 mph31.8 mph+1.8 mph
40 mph42.4 mph+2.4 mph
50 mph53.0 mph+3.0 mph
60 mph63.7 mph+3.7 mph
65 mph69.0 mph+4.0 mph
70 mph74.3 mph+4.3 mph
75 mph79.6 mph+4.6 mph
80 mph84.9 mph+4.9 mph

Each size on its own

Questions

Which is bigger, 185/75R13 or 185/85R13?
185/85R13 is taller by 1.46 inches (25.38" vs 23.93"). 185/75R13 is the same width.
Can I replace 185/75R13 with 185/85R13?
It is not recommended without checking carefully. The diameter difference is +6.1%, 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 185/85R13 change my speedometer?
When your speedometer reads 60 mph with 185/85R13 fitted (calibrated for 185/75R13), your real speed is 63.7 mph. Your odometer will under-count miles by about 6.1%.
Will 185/85R13 lift my vehicle?
Ride height changes by half the diameter difference: +0.73 inches of ground clearance at the axle.

Other comparisons