Tire Size Box

245/45R15 vs 245/50R15

245/50R15 compared with 245/45R15

+4.1% diameter, 0.0" width

245/50R15 is 24.65" tall vs 23.68". More than the 3% rule of thumb, so check carefully before switching.

23.7"15" rim4.3"9.6" wide
245/45R15 (solid) compared with 245/50R15 (dashed outline), drawn to scale

With 245/50R15 tires, when your speedometer says 60 mph you are really going

62.4 mph

245/50R15 is +0.96 inches (+4.1%) in overall diameter. That is more than the 3% most shops and makers recommend.

245/45R15245/50R15Difference%
Overall diameter23.68"24.65"+0.96"+4.1%
Section width9.65"9.65"0.00"0.0%
Sidewall height4.34"4.82"+0.48"+11.1%
Circumference74.40"77.43"+3.03"+4.1%
Revolutions per mile851.7818.3−33.3−3.9%

Speedometer difference

If your vehicle came with 245/45R15 and you fit 245/50R15, 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 mph41.6 mph+1.6 mph
50 mph52.0 mph+2.0 mph
60 mph62.4 mph+2.4 mph
65 mph67.6 mph+2.6 mph
70 mph72.9 mph+2.9 mph
75 mph78.1 mph+3.1 mph
80 mph83.3 mph+3.3 mph

Each size on its own

Questions

Which is bigger, 245/45R15 or 245/50R15?
245/50R15 is taller by 0.96 inches (24.65" vs 23.68"). 245/45R15 is the same width.
Can I replace 245/45R15 with 245/50R15?
It is not recommended without checking carefully. The diameter difference is +4.1%, 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 245/50R15 change my speedometer?
When your speedometer reads 60 mph with 245/50R15 fitted (calibrated for 245/45R15), your real speed is 62.4 mph. Your odometer will under-count miles by about 4.1%.
Will 245/50R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.48 inches of ground clearance at the axle.

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