Tire Size Box

235/40R16 vs 235/50R16

235/50R16 compared with 235/40R16

+7.9% diameter, 0.0" width

235/50R16 is 25.25" tall vs 23.40". More than the 3% rule of thumb, so check carefully before switching.

23.4"16" rim3.7"9.3" wide
235/40R16 (solid) compared with 235/50R16 (dashed outline), drawn to scale

With 235/50R16 tires, when your speedometer says 60 mph you are really going

64.7 mph

235/50R16 is +1.85 inches (+7.9%) in overall diameter. That is more than the 3% most shops and makers recommend.

235/40R16235/50R16Difference%
Overall diameter23.40"25.25"+1.85"+7.9%
Section width9.25"9.25"0.00"0.0%
Sidewall height3.70"4.63"+0.93"+25.0%
Circumference73.52"79.33"+5.81"+7.9%
Revolutions per mile861.8798.7−63.2−7.3%

Speedometer difference

If your vehicle came with 235/40R16 and you fit 235/50R16, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.6 mph+1.6 mph
30 mph32.4 mph+2.4 mph
40 mph43.2 mph+3.2 mph
50 mph54.0 mph+4.0 mph
60 mph64.7 mph+4.7 mph
65 mph70.1 mph+5.1 mph
70 mph75.5 mph+5.5 mph
75 mph80.9 mph+5.9 mph
80 mph86.3 mph+6.3 mph

Each size on its own

Questions

Which is bigger, 235/40R16 or 235/50R16?
235/50R16 is taller by 1.85 inches (25.25" vs 23.40"). 235/40R16 is the same width.
Can I replace 235/40R16 with 235/50R16?
It is not recommended without checking carefully. The diameter difference is +7.9%, 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 235/50R16 change my speedometer?
When your speedometer reads 60 mph with 235/50R16 fitted (calibrated for 235/40R16), your real speed is 64.7 mph. Your odometer will under-count miles by about 7.9%.
Will 235/50R16 lift my vehicle?
Ride height changes by half the diameter difference: +0.93 inches of ground clearance at the axle.

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