Tire Size Box

335/50R18 vs 335/55R18

335/55R18 compared with 335/50R18

+4.2% diameter, 0.0" width

335/55R18 is 32.51" tall vs 31.19". More than the 3% rule of thumb, so check carefully before switching.

31.2"18" rim6.6"13.2" wide
335/50R18 (solid) compared with 335/55R18 (dashed outline), drawn to scale

With 335/55R18 tires, when your speedometer says 60 mph you are really going

62.5 mph

335/55R18 is +1.32 inches (+4.2%) in overall diameter. That is more than the 3% most shops and makers recommend.

335/50R18335/55R18Difference%
Overall diameter31.19"32.51"+1.32"+4.2%
Section width13.19"13.19"0.00"0.0%
Sidewall height6.59"7.25"+0.66"+10.0%
Circumference97.98"102.13"+4.14"+4.2%
Revolutions per mile646.6620.4−26.2−4.1%

Speedometer difference

If your vehicle came with 335/50R18 and you fit 335/55R18, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.8 mph+0.8 mph
30 mph31.3 mph+1.3 mph
40 mph41.7 mph+1.7 mph
50 mph52.1 mph+2.1 mph
60 mph62.5 mph+2.5 mph
65 mph67.7 mph+2.7 mph
70 mph73.0 mph+3.0 mph
75 mph78.2 mph+3.2 mph
80 mph83.4 mph+3.4 mph

Each size on its own

Questions

Which is bigger, 335/50R18 or 335/55R18?
335/55R18 is taller by 1.32 inches (32.51" vs 31.19"). 335/50R18 is the same width.
Can I replace 335/50R18 with 335/55R18?
It is not recommended without checking carefully. The diameter difference is +4.2%, 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 335/55R18 change my speedometer?
When your speedometer reads 60 mph with 335/55R18 fitted (calibrated for 335/50R18), your real speed is 62.5 mph. Your odometer will under-count miles by about 4.2%.
Will 335/55R18 lift my vehicle?
Ride height changes by half the diameter difference: +0.66 inches of ground clearance at the axle.

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