Tire Size Box

205/50R15 vs 205/55R15

205/55R15 compared with 205/50R15

+3.5% diameter, 0.0" width

205/55R15 is 23.88" tall vs 23.07". More than the 3% rule of thumb, so check carefully before switching.

23.1"15" rim4.0"8.1" wide
205/50R15 (solid) compared with 205/55R15 (dashed outline), drawn to scale

With 205/55R15 tires, when your speedometer says 60 mph you are really going

62.1 mph

205/55R15 is +0.81 inches (+3.5%) in overall diameter. That is more than the 3% most shops and makers recommend.

205/50R15205/55R15Difference%
Overall diameter23.07"23.88"+0.81"+3.5%
Section width8.07"8.07"0.00"0.0%
Sidewall height4.04"4.44"+0.40"+10.0%
Circumference72.48"75.01"+2.54"+3.5%
Revolutions per mile874.2844.6−29.5−3.4%

Speedometer difference

If your vehicle came with 205/50R15 and you fit 205/55R15, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.7 mph+0.7 mph
30 mph31.0 mph+1.0 mph
40 mph41.4 mph+1.4 mph
50 mph51.7 mph+1.7 mph
60 mph62.1 mph+2.1 mph
65 mph67.3 mph+2.3 mph
70 mph72.4 mph+2.4 mph
75 mph77.6 mph+2.6 mph
80 mph82.8 mph+2.8 mph

Each size on its own

Questions

Which is bigger, 205/50R15 or 205/55R15?
205/55R15 is taller by 0.81 inches (23.88" vs 23.07"). 205/50R15 is the same width.
Can I replace 205/50R15 with 205/55R15?
It is not recommended without checking carefully. The diameter difference is +3.5%, 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 205/55R15 change my speedometer?
When your speedometer reads 60 mph with 205/55R15 fitted (calibrated for 205/50R15), your real speed is 62.1 mph. Your odometer will under-count miles by about 3.5%.
Will 205/55R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.40 inches of ground clearance at the axle.

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