Tire Size Box

235/50R15 vs 235/55R15

235/55R15 compared with 235/50R15

+3.8% diameter, 0.0" width

235/55R15 is 25.18" tall vs 24.25". More than the 3% rule of thumb, so check carefully before switching.

24.3"15" rim4.6"9.3" wide
235/50R15 (solid) compared with 235/55R15 (dashed outline), drawn to scale

With 235/55R15 tires, when your speedometer says 60 mph you are really going

62.3 mph

235/55R15 is +0.93 inches (+3.8%) in overall diameter. That is more than the 3% most shops and makers recommend.

235/50R15235/55R15Difference%
Overall diameter24.25"25.18"+0.93"+3.8%
Section width9.25"9.25"0.00"0.0%
Sidewall height4.63"5.09"+0.46"+10.0%
Circumference76.19"79.10"+2.91"+3.8%
Revolutions per mile831.6801.0−30.6−3.7%

Speedometer difference

If your vehicle came with 235/50R15 and you fit 235/55R15, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.8 mph+0.8 mph
30 mph31.1 mph+1.1 mph
40 mph41.5 mph+1.5 mph
50 mph51.9 mph+1.9 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, 235/50R15 or 235/55R15?
235/55R15 is taller by 0.93 inches (25.18" vs 24.25"). 235/50R15 is the same width.
Can I replace 235/50R15 with 235/55R15?
It is not recommended without checking carefully. The diameter difference is +3.8%, 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 235/55R15 change my speedometer?
When your speedometer reads 60 mph with 235/55R15 fitted (calibrated for 235/50R15), your real speed is 62.3 mph. Your odometer will under-count miles by about 3.8%.
Will 235/55R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.46 inches of ground clearance at the axle.

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