Tire Size Box

185/60R15 vs 185/65R15

185/65R15 compared with 185/60R15

+3.1% diameter, 0.0" width

185/65R15 is 24.47" tall vs 23.74". More than the 3% rule of thumb, so check carefully before switching.

23.7"15" rim4.4"7.3" wide
185/60R15 (solid) compared with 185/65R15 (dashed outline), drawn to scale

With 185/65R15 tires, when your speedometer says 60 mph you are really going

61.8 mph

185/65R15 is +0.73 inches (+3.1%) in overall diameter. That is more than the 3% most shops and makers recommend.

185/60R15185/65R15Difference%
Overall diameter23.74"24.47"+0.73"+3.1%
Section width7.28"7.28"0.00"0.0%
Sidewall height4.37"4.73"+0.36"+8.3%
Circumference74.58"76.87"+2.29"+3.1%
Revolutions per mile849.5824.2−25.3−3.0%

Speedometer difference

If your vehicle came with 185/60R15 and you fit 185/65R15, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.6 mph+0.6 mph
30 mph30.9 mph+0.9 mph
40 mph41.2 mph+1.2 mph
50 mph51.5 mph+1.5 mph
60 mph61.8 mph+1.8 mph
65 mph67.0 mph+2.0 mph
70 mph72.1 mph+2.1 mph
75 mph77.3 mph+2.3 mph
80 mph82.5 mph+2.5 mph

Each size on its own

Questions

Which is bigger, 185/60R15 or 185/65R15?
185/65R15 is taller by 0.73 inches (24.47" vs 23.74"). 185/60R15 is the same width.
Can I replace 185/60R15 with 185/65R15?
It is not recommended without checking carefully. The diameter difference is +3.1%, 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 185/65R15 change my speedometer?
When your speedometer reads 60 mph with 185/65R15 fitted (calibrated for 185/60R15), your real speed is 61.8 mph. Your odometer will under-count miles by about 3.1%.
Will 185/65R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.36 inches of ground clearance at the axle.

Other comparisons