Tire Size Box

225/45R15 vs 225/50R15

225/50R15 compared with 225/45R15

+3.9% diameter, 0.0" width

225/50R15 is 23.86" tall vs 22.97". More than the 3% rule of thumb, so check carefully before switching.

23.0"15" rim4.0"8.9" wide
225/45R15 (solid) compared with 225/50R15 (dashed outline), drawn to scale

With 225/50R15 tires, when your speedometer says 60 mph you are really going

62.3 mph

225/50R15 is +0.89 inches (+3.9%) in overall diameter. That is more than the 3% most shops and makers recommend.

225/45R15225/50R15Difference%
Overall diameter22.97"23.86"+0.89"+3.9%
Section width8.86"8.86"0.00"0.0%
Sidewall height3.99"4.43"+0.44"+11.1%
Circumference72.17"74.95"+2.78"+3.9%
Revolutions per mile877.9845.3−32.6−3.7%

Speedometer difference

If your vehicle came with 225/45R15 and you fit 225/50R15, 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 mph41.5 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, 225/45R15 or 225/50R15?
225/50R15 is taller by 0.89 inches (23.86" vs 22.97"). 225/45R15 is the same width.
Can I replace 225/45R15 with 225/50R15?
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 225/50R15 change my speedometer?
When your speedometer reads 60 mph with 225/50R15 fitted (calibrated for 225/45R15), your real speed is 62.3 mph. Your odometer will under-count miles by about 3.9%.
Will 225/50R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.44 inches of ground clearance at the axle.

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