Tire Size Box

235/45R17 vs 235/50R17

235/50R17 compared with 235/45R17

+3.7% diameter, 0.0" width

235/50R17 is 26.25" tall vs 25.33". More than the 3% rule of thumb, so check carefully before switching.

25.3"17" rim4.2"9.3" wide
235/45R17 (solid) compared with 235/50R17 (dashed outline), drawn to scale

With 235/50R17 tires, when your speedometer says 60 mph you are really going

62.2 mph

235/50R17 is +0.93 inches (+3.7%) in overall diameter. That is more than the 3% most shops and makers recommend.

235/45R17235/50R17Difference%
Overall diameter25.33"26.25"+0.93"+3.7%
Section width9.25"9.25"0.00"0.0%
Sidewall height4.16"4.63"+0.46"+11.1%
Circumference79.57"82.47"+2.91"+3.7%
Revolutions per mile796.3768.3−28.1−3.5%

Speedometer difference

If your vehicle came with 235/45R17 and you fit 235/50R17, 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 mph72.6 mph+2.6 mph
75 mph77.7 mph+2.7 mph
80 mph82.9 mph+2.9 mph

Each size on its own

Questions

Which is bigger, 235/45R17 or 235/50R17?
235/50R17 is taller by 0.93 inches (26.25" vs 25.33"). 235/45R17 is the same width.
Can I replace 235/45R17 with 235/50R17?
It is not recommended without checking carefully. The diameter difference is +3.7%, 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 235/50R17 change my speedometer?
When your speedometer reads 60 mph with 235/50R17 fitted (calibrated for 235/45R17), your real speed is 62.2 mph. Your odometer will under-count miles by about 3.7%.
Will 235/50R17 lift my vehicle?
Ride height changes by half the diameter difference: +0.46 inches of ground clearance at the axle.

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