345/50R19 vs 345/55R19

345/55R19 compared with 345/50R19

+4.2% diameter, 0.0" width

345/55R19 is 33.94" tall vs 32.58". More than the 3% rule of thumb, so check carefully before switching.

32.6"19" rim6.8"13.6" wide
345/50R19 (solid) compared with 345/55R19 (dashed outline), drawn to scale

With 345/55R19 tires, when your speedometer says 60 mph you are really going

62.5 mph

345/55R19 is +1.36 inches (+4.2%) in overall diameter. That is more than the 3% most shops and makers recommend.

345/50R19345/55R19Difference%
Overall diameter32.58"33.94"+1.36"+4.2%
Section width13.58"13.58"0.00"0.0%
Sidewall height6.79"7.47"+0.68"+10.0%
Circumference102.36"106.63"+4.27"+4.2%
Revolutions per mile619.0594.2−24.8−4.0%

Speedometer difference

If your vehicle came with 345/50R19 and you fit 345/55R19, 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 mph72.9 mph+2.9 mph
75 mph78.1 mph+3.1 mph
80 mph83.3 mph+3.3 mph

Each size on its own

Questions

Which is bigger, 345/50R19 or 345/55R19?
345/55R19 is taller by 1.36 inches (33.94" vs 32.58"). 345/50R19 is the same width.
Can I replace 345/50R19 with 345/55R19?
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 345/55R19 change my speedometer?
When your speedometer reads 60 mph with 345/55R19 fitted (calibrated for 345/50R19), your real speed is 62.5 mph. Your odometer will under-count miles by about 4.2%.
Will 345/55R19 lift my vehicle?
Ride height changes by half the diameter difference: +0.68 inches of ground clearance at the axle.

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