Tire Size Box

165/55R15 vs 165/65R15

165/65R15 compared with 165/55R15

+5.9% diameter, 0.0" width

165/65R15 is 23.44" tall vs 22.15". More than the 3% rule of thumb, so check carefully before switching.

22.1"15" rim3.6"6.5" wide
165/55R15 (solid) compared with 165/65R15 (dashed outline), drawn to scale

With 165/65R15 tires, when your speedometer says 60 mph you are really going

63.5 mph

165/65R15 is +1.30 inches (+5.9%) in overall diameter. That is more than the 3% most shops and makers recommend.

165/55R15165/65R15Difference%
Overall diameter22.15"23.44"+1.30"+5.9%
Section width6.50"6.50"0.00"0.0%
Sidewall height3.57"4.22"+0.65"+18.2%
Circumference69.57"73.65"+4.08"+5.9%
Revolutions per mile910.7860.2−50.5−5.5%

Speedometer difference

If your vehicle came with 165/55R15 and you fit 165/65R15, 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 mph42.3 mph+2.3 mph
50 mph52.9 mph+2.9 mph
60 mph63.5 mph+3.5 mph
65 mph68.8 mph+3.8 mph
70 mph74.1 mph+4.1 mph
75 mph79.4 mph+4.4 mph
80 mph84.7 mph+4.7 mph

Each size on its own

Questions

Which is bigger, 165/55R15 or 165/65R15?
165/65R15 is taller by 1.30 inches (23.44" vs 22.15"). 165/55R15 is the same width.
Can I replace 165/55R15 with 165/65R15?
It is not recommended without checking carefully. The diameter difference is +5.9%, 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 165/65R15 change my speedometer?
When your speedometer reads 60 mph with 165/65R15 fitted (calibrated for 165/55R15), your real speed is 63.5 mph. Your odometer will under-count miles by about 5.9%.
Will 165/65R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.65 inches of ground clearance at the axle.

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