Tire Size Box

235/40R22 vs 235/50R22

235/50R22 compared with 235/40R22

+6.3% diameter, 0.0" width

235/50R22 is 31.25" tall vs 29.40". More than the 3% rule of thumb, so check carefully before switching.

29.4"22" rim3.7"9.3" wide
235/40R22 (solid) compared with 235/50R22 (dashed outline), drawn to scale

With 235/50R22 tires, when your speedometer says 60 mph you are really going

63.8 mph

235/50R22 is +1.85 inches (+6.3%) in overall diameter. That is more than the 3% most shops and makers recommend.

235/40R22235/50R22Difference%
Overall diameter29.40"31.25"+1.85"+6.3%
Section width9.25"9.25"0.00"0.0%
Sidewall height3.70"4.63"+0.93"+25.0%
Circumference92.37"98.18"+5.81"+6.3%
Revolutions per mile686.0645.3−40.6−5.9%

Speedometer difference

If your vehicle came with 235/40R22 and you fit 235/50R22, 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 mph53.1 mph+3.1 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 mph85.0 mph+5.0 mph

Each size on its own

Questions

Which is bigger, 235/40R22 or 235/50R22?
235/50R22 is taller by 1.85 inches (31.25" vs 29.40"). 235/40R22 is the same width.
Can I replace 235/40R22 with 235/50R22?
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 235/50R22 change my speedometer?
When your speedometer reads 60 mph with 235/50R22 fitted (calibrated for 235/40R22), your real speed is 63.8 mph. Your odometer will under-count miles by about 6.3%.
Will 235/50R22 lift my vehicle?
Ride height changes by half the diameter difference: +0.93 inches of ground clearance at the axle.

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