Tire Size Box

225/45R17 vs 225/55R17

225/55R17 compared with 225/45R17

+7.1% diameter, 0.0" width

225/55R17 is 26.74" tall vs 24.97". More than the 3% rule of thumb, so check carefully before switching.

25.0"17" rim4.0"8.9" wide
225/45R17 (solid) compared with 225/55R17 (dashed outline), drawn to scale

With 225/55R17 tires, when your speedometer says 60 mph you are really going

64.3 mph

225/55R17 is +1.77 inches (+7.1%) in overall diameter. That is more than the 3% most shops and makers recommend.

225/45R17225/55R17Difference%
Overall diameter24.97"26.74"+1.77"+7.1%
Section width8.86"8.86"0.00"0.0%
Sidewall height3.99"4.87"+0.89"+22.2%
Circumference78.45"84.02"+5.57"+7.1%
Revolutions per mile807.6754.1−53.5−6.6%

Speedometer difference

If your vehicle came with 225/45R17 and you fit 225/55R17, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.4 mph+1.4 mph
30 mph32.1 mph+2.1 mph
40 mph42.8 mph+2.8 mph
50 mph53.5 mph+3.5 mph
60 mph64.3 mph+4.3 mph
65 mph69.6 mph+4.6 mph
70 mph75.0 mph+5.0 mph
75 mph80.3 mph+5.3 mph
80 mph85.7 mph+5.7 mph

Each size on its own

Questions

Which is bigger, 225/45R17 or 225/55R17?
225/55R17 is taller by 1.77 inches (26.74" vs 24.97"). 225/45R17 is the same width.
Can I replace 225/45R17 with 225/55R17?
It is not recommended without checking carefully. The diameter difference is +7.1%, 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 225/55R17 change my speedometer?
When your speedometer reads 60 mph with 225/55R17 fitted (calibrated for 225/45R17), your real speed is 64.3 mph. Your odometer will under-count miles by about 7.1%.
Will 225/55R17 lift my vehicle?
Ride height changes by half the diameter difference: +0.89 inches of ground clearance at the axle.

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