Tire Size Box

335/40R21 vs 335/50R21

335/50R21 compared with 335/40R21

+8.4% diameter, 0.0" width

335/50R21 is 34.19" tall vs 31.55". More than the 3% rule of thumb, so check carefully before switching.

31.6"21" rim5.3"13.2" wide
335/40R21 (solid) compared with 335/50R21 (dashed outline), drawn to scale

With 335/50R21 tires, when your speedometer says 60 mph you are really going

65.0 mph

335/50R21 is +2.64 inches (+8.4%) in overall diameter. That is more than the 3% most shops and makers recommend.

335/40R21335/50R21Difference%
Overall diameter31.55"34.19"+2.64"+8.4%
Section width13.19"13.19"0.00"0.0%
Sidewall height5.28"6.59"+1.32"+25.0%
Circumference99.12"107.41"+8.29"+8.4%
Revolutions per mile639.2589.9−49.3−7.7%

Speedometer difference

If your vehicle came with 335/40R21 and you fit 335/50R21, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.7 mph+1.7 mph
30 mph32.5 mph+2.5 mph
40 mph43.3 mph+3.3 mph
50 mph54.2 mph+4.2 mph
60 mph65.0 mph+5.0 mph
65 mph70.4 mph+5.4 mph
70 mph75.9 mph+5.9 mph
75 mph81.3 mph+6.3 mph
80 mph86.7 mph+6.7 mph

Each size on its own

Questions

Which is bigger, 335/40R21 or 335/50R21?
335/50R21 is taller by 2.64 inches (34.19" vs 31.55"). 335/40R21 is the same width.
Can I replace 335/40R21 with 335/50R21?
It is not recommended without checking carefully. The diameter difference is +8.4%, 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 335/50R21 change my speedometer?
When your speedometer reads 60 mph with 335/50R21 fitted (calibrated for 335/40R21), your real speed is 65.0 mph. Your odometer will under-count miles by about 8.4%.
Will 335/50R21 lift my vehicle?
Ride height changes by half the diameter difference: +1.32 inches of ground clearance at the axle.

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