Tire Size Box

205/55R15 vs 225/55R15

225/55R15 compared with 205/55R15

+3.6% diameter, +0.8" width

225/55R15 is 24.74" tall vs 23.88". More than the 3% rule of thumb, so check carefully before switching.

23.9"15" rim4.4"8.1" wide
205/55R15 (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 +0.87 inches (+3.6%) in overall diameter. That is more than the 3% most shops and makers recommend.

205/55R15225/55R15Difference%
Overall diameter23.88"24.74"+0.87"+3.6%
Section width8.07"8.86"+0.79"+9.8%
Sidewall height4.44"4.87"+0.43"+9.8%
Circumference75.01"77.74"+2.72"+3.6%
Revolutions per mile844.6815.1−29.6−3.5%

Speedometer difference

If your vehicle came with 205/55R15 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 mph51.8 mph+1.8 mph
60 mph62.2 mph+2.2 mph
65 mph67.4 mph+2.4 mph
70 mph72.5 mph+2.5 mph
75 mph77.7 mph+2.7 mph
80 mph82.9 mph+2.9 mph

Each size on its own

Questions

Which is bigger, 205/55R15 or 225/55R15?
225/55R15 is taller by 0.87 inches (24.74" vs 23.88"). 225/55R15 is wider by 0.79 inches.
Can I replace 205/55R15 with 225/55R15?
It is not recommended without checking carefully. The diameter difference is +3.6%, 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 205/55R15), your real speed is 62.2 mph. Your odometer will under-count miles by about 3.6%.
Will 225/55R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.43 inches of ground clearance at the axle.

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