Tire Size Box

335/45R21 vs 335/55R21

335/55R21 compared with 335/45R21

+8.0% diameter, 0.0" width

335/55R21 is 35.51" tall vs 32.87". More than the 3% rule of thumb, so check carefully before switching.

32.9"21" rim5.9"13.2" wide
335/45R21 (solid) compared with 335/55R21 (dashed outline), drawn to scale

With 335/55R21 tires, when your speedometer says 60 mph you are really going

64.8 mph

335/55R21 is +2.64 inches (+8.0%) in overall diameter. That is more than the 3% most shops and makers recommend.

335/45R21335/55R21Difference%
Overall diameter32.87"35.51"+2.64"+8.0%
Section width13.19"13.19"0.00"0.0%
Sidewall height5.94"7.25"+1.32"+22.2%
Circumference103.26"111.55"+8.29"+8.0%
Revolutions per mile613.6568.0−45.6−7.4%

Speedometer difference

If your vehicle came with 335/45R21 and you fit 335/55R21, 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 mph64.8 mph+4.8 mph
65 mph70.2 mph+5.2 mph
70 mph75.6 mph+5.6 mph
75 mph81.0 mph+6.0 mph
80 mph86.4 mph+6.4 mph

Each size on its own

Questions

Which is bigger, 335/45R21 or 335/55R21?
335/55R21 is taller by 2.64 inches (35.51" vs 32.87"). 335/45R21 is the same width.
Can I replace 335/45R21 with 335/55R21?
It is not recommended without checking carefully. The diameter difference is +8.0%, 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 335/55R21 change my speedometer?
When your speedometer reads 60 mph with 335/55R21 fitted (calibrated for 335/45R21), your real speed is 64.8 mph. Your odometer will under-count miles by about 8.0%.
Will 335/55R21 lift my vehicle?
Ride height changes by half the diameter difference: +1.32 inches of ground clearance at the axle.

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