Tire Size Box

345/50R19 vs 325/55R19

325/55R19 compared with 345/50R19

+1.5% diameter, −0.8" width

325/55R19 is 33.07" tall vs 32.58". Within the 3% rule, so usually interchangeable.

32.6"19" rim6.8"13.6" wide
345/50R19 (solid) compared with 325/55R19 (dashed outline), drawn to scale

With 325/55R19 tires, when your speedometer says 60 mph you are really going

60.9 mph

325/55R19 is +0.49 inches (+1.5%) in overall diameter. That is within the 3% most shops and makers allow.

345/50R19325/55R19Difference%
Overall diameter32.58"33.07"+0.49"+1.5%
Section width13.58"12.80"−0.79"−5.8%
Sidewall height6.79"7.04"+0.25"+3.6%
Circumference102.36"103.91"+1.55"+1.5%
Revolutions per mile619.0609.8−9.2−1.5%

Speedometer difference

If your vehicle came with 345/50R19 and you fit 325/55R19, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.3 mph+0.3 mph
30 mph30.5 mph+0.5 mph
40 mph40.6 mph+0.6 mph
50 mph50.8 mph+0.8 mph
60 mph60.9 mph+0.9 mph
65 mph66.0 mph+1.0 mph
70 mph71.1 mph+1.1 mph
75 mph76.1 mph+1.1 mph
80 mph81.2 mph+1.2 mph

Each size on its own

Questions

Which is bigger, 345/50R19 or 325/55R19?
325/55R19 is taller by 0.49 inches (33.07" vs 32.58"). 345/50R19 is wider by 0.79 inches.
Can I replace 345/50R19 with 325/55R19?
Usually, yes. The diameter difference is +1.5%, inside the 3% rule of thumb most tire shops use. Check that the wider or taller tire clears your suspension and fenders, and that its load index meets your placard.
How much will 325/55R19 change my speedometer?
When your speedometer reads 60 mph with 325/55R19 fitted (calibrated for 345/50R19), your real speed is 60.9 mph. Your odometer will under-count miles by about 1.5%.
Will 325/55R19 lift my vehicle?
Ride height changes by half the diameter difference: +0.25 inches of ground clearance at the axle.

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