Tire Size Box

245/50R15 vs 245/55R15

245/55R15 compared with 245/50R15

+3.9% diameter, 0.0" width

245/55R15 is 25.61" tall vs 24.65". More than the 3% rule of thumb, so check carefully before switching.

24.6"15" rim4.8"9.6" wide
245/50R15 (solid) compared with 245/55R15 (dashed outline), drawn to scale

With 245/55R15 tires, when your speedometer says 60 mph you are really going

62.3 mph

245/55R15 is +0.96 inches (+3.9%) in overall diameter. That is more than the 3% most shops and makers recommend.

245/50R15245/55R15Difference%
Overall diameter24.65"25.61"+0.96"+3.9%
Section width9.65"9.65"0.00"0.0%
Sidewall height4.82"5.31"+0.48"+10.0%
Circumference77.43"80.46"+3.03"+3.9%
Revolutions per mile818.3787.5−30.8−3.8%

Speedometer difference

If your vehicle came with 245/50R15 and you fit 245/55R15, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.8 mph+0.8 mph
30 mph31.2 mph+1.2 mph
40 mph41.6 mph+1.6 mph
50 mph52.0 mph+2.0 mph
60 mph62.3 mph+2.3 mph
65 mph67.5 mph+2.5 mph
70 mph72.7 mph+2.7 mph
75 mph77.9 mph+2.9 mph
80 mph83.1 mph+3.1 mph

Each size on its own

Questions

Which is bigger, 245/50R15 or 245/55R15?
245/55R15 is taller by 0.96 inches (25.61" vs 24.65"). 245/50R15 is the same width.
Can I replace 245/50R15 with 245/55R15?
It is not recommended without checking carefully. The diameter difference is +3.9%, 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 245/55R15 change my speedometer?
When your speedometer reads 60 mph with 245/55R15 fitted (calibrated for 245/50R15), your real speed is 62.3 mph. Your odometer will under-count miles by about 3.9%.
Will 245/55R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.48 inches of ground clearance at the axle.

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