Tire Size Box

285/45R17 vs 285/50R17

285/50R17 compared with 285/45R17

+4.1% diameter, 0.0" width

285/50R17 is 28.22" tall vs 27.10". More than the 3% rule of thumb, so check carefully before switching.

27.1"17" rim5.0"11.2" wide
285/45R17 (solid) compared with 285/50R17 (dashed outline), drawn to scale

With 285/50R17 tires, when your speedometer says 60 mph you are really going

62.5 mph

285/50R17 is +1.12 inches (+4.1%) in overall diameter. That is more than the 3% most shops and makers recommend.

285/45R17285/50R17Difference%
Overall diameter27.10"28.22"+1.12"+4.1%
Section width11.22"11.22"0.00"0.0%
Sidewall height5.05"5.61"+0.56"+11.1%
Circumference85.13"88.66"+3.53"+4.1%
Revolutions per mile744.3714.7−29.6−4.0%

Speedometer difference

If your vehicle came with 285/45R17 and you fit 285/50R17, 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 mph41.7 mph+1.7 mph
50 mph52.1 mph+2.1 mph
60 mph62.5 mph+2.5 mph
65 mph67.7 mph+2.7 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, 285/45R17 or 285/50R17?
285/50R17 is taller by 1.12 inches (28.22" vs 27.10"). 285/45R17 is the same width.
Can I replace 285/45R17 with 285/50R17?
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 285/50R17 change my speedometer?
When your speedometer reads 60 mph with 285/50R17 fitted (calibrated for 285/45R17), your real speed is 62.5 mph. Your odometer will under-count miles by about 4.1%.
Will 285/50R17 lift my vehicle?
Ride height changes by half the diameter difference: +0.56 inches of ground clearance at the axle.

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