Tire Size Box

215/40R17 vs 215/50R17

215/50R17 compared with 215/40R17

+7.1% diameter, 0.0" width

215/50R17 is 25.46" tall vs 23.77". More than the 3% rule of thumb, so check carefully before switching.

23.8"17" rim3.4"8.5" wide
215/40R17 (solid) compared with 215/50R17 (dashed outline), drawn to scale

With 215/50R17 tires, when your speedometer says 60 mph you are really going

64.3 mph

215/50R17 is +1.69 inches (+7.1%) in overall diameter. That is more than the 3% most shops and makers recommend.

215/40R17215/50R17Difference%
Overall diameter23.77"25.46"+1.69"+7.1%
Section width8.46"8.46"0.00"0.0%
Sidewall height3.39"4.23"+0.85"+25.0%
Circumference74.68"80.00"+5.32"+7.1%
Revolutions per mile848.4792.0−56.4−6.6%

Speedometer difference

If your vehicle came with 215/40R17 and you fit 215/50R17, 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 mph53.6 mph+3.6 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, 215/40R17 or 215/50R17?
215/50R17 is taller by 1.69 inches (25.46" vs 23.77"). 215/40R17 is the same width.
Can I replace 215/40R17 with 215/50R17?
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 215/50R17 change my speedometer?
When your speedometer reads 60 mph with 215/50R17 fitted (calibrated for 215/40R17), your real speed is 64.3 mph. Your odometer will under-count miles by about 7.1%.
Will 215/50R17 lift my vehicle?
Ride height changes by half the diameter difference: +0.85 inches of ground clearance at the axle.

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