Tire Size Box

185/65R17 vs 185/75R17

185/75R17 compared with 185/65R17

+5.5% diameter, 0.0" width

185/75R17 is 27.93" tall vs 26.47". More than the 3% rule of thumb, so check carefully before switching.

26.5"17" rim4.7"7.3" wide
185/65R17 (solid) compared with 185/75R17 (dashed outline), drawn to scale

With 185/75R17 tires, when your speedometer says 60 mph you are really going

63.3 mph

185/75R17 is +1.46 inches (+5.5%) in overall diameter. That is more than the 3% most shops and makers recommend.

185/65R17185/75R17Difference%
Overall diameter26.47"27.93"+1.46"+5.5%
Section width7.28"7.28"0.00"0.0%
Sidewall height4.73"5.46"+0.73"+15.4%
Circumference83.15"87.73"+4.58"+5.5%
Revolutions per mile762.0722.2−39.7−5.2%

Speedometer difference

If your vehicle came with 185/65R17 and you fit 185/75R17, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.1 mph+1.1 mph
30 mph31.7 mph+1.7 mph
40 mph42.2 mph+2.2 mph
50 mph52.8 mph+2.8 mph
60 mph63.3 mph+3.3 mph
65 mph68.6 mph+3.6 mph
70 mph73.9 mph+3.9 mph
75 mph79.1 mph+4.1 mph
80 mph84.4 mph+4.4 mph

Each size on its own

Questions

Which is bigger, 185/65R17 or 185/75R17?
185/75R17 is taller by 1.46 inches (27.93" vs 26.47"). 185/65R17 is the same width.
Can I replace 185/65R17 with 185/75R17?
It is not recommended without checking carefully. The diameter difference is +5.5%, 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 185/75R17 change my speedometer?
When your speedometer reads 60 mph with 185/75R17 fitted (calibrated for 185/65R17), your real speed is 63.3 mph. Your odometer will under-count miles by about 5.5%.
Will 185/75R17 lift my vehicle?
Ride height changes by half the diameter difference: +0.73 inches of ground clearance at the axle.

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