Tire Size Box

165/65R15 vs 165/75R15

165/75R15 compared with 165/65R15

+5.5% diameter, 0.0" width

165/75R15 is 24.74" tall vs 23.44". More than the 3% rule of thumb, so check carefully before switching.

23.4"15" rim4.2"6.5" wide
165/65R15 (solid) compared with 165/75R15 (dashed outline), drawn to scale

With 165/75R15 tires, when your speedometer says 60 mph you are really going

63.3 mph

165/75R15 is +1.30 inches (+5.5%) in overall diameter. That is more than the 3% most shops and makers recommend.

165/65R15165/75R15Difference%
Overall diameter23.44"24.74"+1.30"+5.5%
Section width6.50"6.50"0.00"0.0%
Sidewall height4.22"4.87"+0.65"+15.4%
Circumference73.65"77.74"+4.08"+5.5%
Revolutions per mile860.2815.1−45.2−5.3%

Speedometer difference

If your vehicle came with 165/65R15 and you fit 165/75R15, 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 mph79.2 mph+4.2 mph
80 mph84.4 mph+4.4 mph

Each size on its own

Questions

Which is bigger, 165/65R15 or 165/75R15?
165/75R15 is taller by 1.30 inches (24.74" vs 23.44"). 165/65R15 is the same width.
Can I replace 165/65R15 with 165/75R15?
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 165/75R15 change my speedometer?
When your speedometer reads 60 mph with 165/75R15 fitted (calibrated for 165/65R15), your real speed is 63.3 mph. Your odometer will under-count miles by about 5.5%.
Will 165/75R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.65 inches of ground clearance at the axle.

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