Tire Size Box

225/55R15 vs 225/65R15

225/65R15 compared with 225/55R15

+7.2% diameter, 0.0" width

225/65R15 is 26.52" tall vs 24.74". More than the 3% rule of thumb, so check carefully before switching.

24.7"15" rim4.9"8.9" wide
225/55R15 (solid) compared with 225/65R15 (dashed outline), drawn to scale

With 225/65R15 tires, when your speedometer says 60 mph you are really going

64.3 mph

225/65R15 is +1.77 inches (+7.2%) in overall diameter. That is more than the 3% most shops and makers recommend.

225/55R15225/65R15Difference%
Overall diameter24.74"26.52"+1.77"+7.2%
Section width8.86"8.86"0.00"0.0%
Sidewall height4.87"5.76"+0.89"+18.2%
Circumference77.74"83.30"+5.57"+7.2%
Revolutions per mile815.1760.6−54.5−6.7%

Speedometer difference

If your vehicle came with 225/55R15 and you fit 225/65R15, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.4 mph+1.4 mph
30 mph32.1 mph+2.1 mph
40 mph42.9 mph+2.9 mph
50 mph53.6 mph+3.6 mph
60 mph64.3 mph+4.3 mph
65 mph69.7 mph+4.7 mph
70 mph75.0 mph+5.0 mph
75 mph80.4 mph+5.4 mph
80 mph85.7 mph+5.7 mph

Each size on its own

Questions

Which is bigger, 225/55R15 or 225/65R15?
225/65R15 is taller by 1.77 inches (26.52" vs 24.74"). 225/55R15 is the same width.
Can I replace 225/55R15 with 225/65R15?
It is not recommended without checking carefully. The diameter difference is +7.2%, 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 225/65R15 change my speedometer?
When your speedometer reads 60 mph with 225/65R15 fitted (calibrated for 225/55R15), your real speed is 64.3 mph. Your odometer will under-count miles by about 7.2%.
Will 225/65R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.89 inches of ground clearance at the axle.

Other comparisons