Tire Size Box

225/50R15 vs 225/55R15

225/55R15 compared with 225/50R15

+3.7% diameter, 0.0" width

225/55R15 is 24.74" tall vs 23.86". More than the 3% rule of thumb, so check carefully before switching.

23.9"15" rim4.4"8.9" wide
225/50R15 (solid) compared with 225/55R15 (dashed outline), drawn to scale

With 225/55R15 tires, when your speedometer says 60 mph you are really going

62.2 mph

225/55R15 is +0.89 inches (+3.7%) in overall diameter. That is more than the 3% most shops and makers recommend.

225/50R15225/55R15Difference%
Overall diameter23.86"24.74"+0.89"+3.7%
Section width8.86"8.86"0.00"0.0%
Sidewall height4.43"4.87"+0.44"+10.0%
Circumference74.95"77.74"+2.78"+3.7%
Revolutions per mile845.3815.1−30.3−3.6%

Speedometer difference

If your vehicle came with 225/50R15 and you fit 225/55R15, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.7 mph+0.7 mph
30 mph31.1 mph+1.1 mph
40 mph41.5 mph+1.5 mph
50 mph51.9 mph+1.9 mph
60 mph62.2 mph+2.2 mph
65 mph67.4 mph+2.4 mph
70 mph72.6 mph+2.6 mph
75 mph77.8 mph+2.8 mph
80 mph83.0 mph+3.0 mph

Each size on its own

Questions

Which is bigger, 225/50R15 or 225/55R15?
225/55R15 is taller by 0.89 inches (24.74" vs 23.86"). 225/50R15 is the same width.
Can I replace 225/50R15 with 225/55R15?
It is not recommended without checking carefully. The diameter difference is +3.7%, 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 225/55R15 change my speedometer?
When your speedometer reads 60 mph with 225/55R15 fitted (calibrated for 225/50R15), your real speed is 62.2 mph. Your odometer will under-count miles by about 3.7%.
Will 225/55R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.44 inches of ground clearance at the axle.

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