Tire Size Box

215/40R20 vs 215/50R20

215/50R20 compared with 215/40R20

+6.3% diameter, 0.0" width

215/50R20 is 28.46" tall vs 26.77". More than the 3% rule of thumb, so check carefully before switching.

26.8"20" rim3.4"8.5" wide
215/40R20 (solid) compared with 215/50R20 (dashed outline), drawn to scale

With 215/50R20 tires, when your speedometer says 60 mph you are really going

63.8 mph

215/50R20 is +1.69 inches (+6.3%) in overall diameter. That is more than the 3% most shops and makers recommend.

215/40R20215/50R20Difference%
Overall diameter26.77"28.46"+1.69"+6.3%
Section width8.46"8.46"0.00"0.0%
Sidewall height3.39"4.23"+0.85"+25.0%
Circumference84.11"89.42"+5.32"+6.3%
Revolutions per mile753.3708.5−44.8−5.9%

Speedometer difference

If your vehicle came with 215/40R20 and you fit 215/50R20, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.3 mph+1.3 mph
30 mph31.9 mph+1.9 mph
40 mph42.5 mph+2.5 mph
50 mph53.2 mph+3.2 mph
60 mph63.8 mph+3.8 mph
65 mph69.1 mph+4.1 mph
70 mph74.4 mph+4.4 mph
75 mph79.7 mph+4.7 mph
80 mph85.1 mph+5.1 mph

Each size on its own

Questions

Which is bigger, 215/40R20 or 215/50R20?
215/50R20 is taller by 1.69 inches (28.46" vs 26.77"). 215/40R20 is the same width.
Can I replace 215/40R20 with 215/50R20?
It is not recommended without checking carefully. The diameter difference is +6.3%, 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 215/50R20 change my speedometer?
When your speedometer reads 60 mph with 215/50R20 fitted (calibrated for 215/40R20), your real speed is 63.8 mph. Your odometer will under-count miles by about 6.3%.
Will 215/50R20 lift my vehicle?
Ride height changes by half the diameter difference: +0.85 inches of ground clearance at the axle.

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