Tire Size Box

335/45R20 vs 335/55R20

335/55R20 compared with 335/45R20

+8.3% diameter, 0.0" width

335/55R20 is 34.51" tall vs 31.87". More than the 3% rule of thumb, so check carefully before switching.

31.9"20" rim5.9"13.2" wide
335/45R20 (solid) compared with 335/55R20 (dashed outline), drawn to scale

With 335/55R20 tires, when your speedometer says 60 mph you are really going

65.0 mph

335/55R20 is +2.64 inches (+8.3%) in overall diameter. That is more than the 3% most shops and makers recommend.

335/45R20335/55R20Difference%
Overall diameter31.87"34.51"+2.64"+8.3%
Section width13.19"13.19"0.00"0.0%
Sidewall height5.94"7.25"+1.32"+22.2%
Circumference100.12"108.41"+8.29"+8.3%
Revolutions per mile632.8584.4−48.4−7.6%

Speedometer difference

If your vehicle came with 335/45R20 and you fit 335/55R20, 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 mph54.1 mph+4.1 mph
60 mph65.0 mph+5.0 mph
65 mph70.4 mph+5.4 mph
70 mph75.8 mph+5.8 mph
75 mph81.2 mph+6.2 mph
80 mph86.6 mph+6.6 mph

Each size on its own

Questions

Which is bigger, 335/45R20 or 335/55R20?
335/55R20 is taller by 2.64 inches (34.51" vs 31.87"). 335/45R20 is the same width.
Can I replace 335/45R20 with 335/55R20?
It is not recommended without checking carefully. The diameter difference is +8.3%, 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 335/55R20 change my speedometer?
When your speedometer reads 60 mph with 335/55R20 fitted (calibrated for 335/45R20), your real speed is 65.0 mph. Your odometer will under-count miles by about 8.3%.
Will 335/55R20 lift my vehicle?
Ride height changes by half the diameter difference: +1.32 inches of ground clearance at the axle.

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