Tire Size Box

315/45R19 vs 315/55R19

315/55R19 compared with 315/45R19

+8.2% diameter, 0.0" width

315/55R19 is 32.64" tall vs 30.16". More than the 3% rule of thumb, so check carefully before switching.

30.2"19" rim5.6"12.4" wide
315/45R19 (solid) compared with 315/55R19 (dashed outline), drawn to scale

With 315/55R19 tires, when your speedometer says 60 mph you are really going

64.9 mph

315/55R19 is +2.48 inches (+8.2%) in overall diameter. That is more than the 3% most shops and makers recommend.

315/45R19315/55R19Difference%
Overall diameter30.16"32.64"+2.48"+8.2%
Section width12.40"12.40"0.00"0.0%
Sidewall height5.58"6.82"+1.24"+22.2%
Circumference94.75"102.55"+7.79"+8.2%
Revolutions per mile668.7617.9−50.8−7.6%

Speedometer difference

If your vehicle came with 315/45R19 and you fit 315/55R19, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.6 mph+1.6 mph
30 mph32.5 mph+2.5 mph
40 mph43.3 mph+3.3 mph
50 mph54.1 mph+4.1 mph
60 mph64.9 mph+4.9 mph
65 mph70.3 mph+5.3 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, 315/45R19 or 315/55R19?
315/55R19 is taller by 2.48 inches (32.64" vs 30.16"). 315/45R19 is the same width.
Can I replace 315/45R19 with 315/55R19?
It is not recommended without checking carefully. The diameter difference is +8.2%, 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 315/55R19 change my speedometer?
When your speedometer reads 60 mph with 315/55R19 fitted (calibrated for 315/45R19), your real speed is 64.9 mph. Your odometer will under-count miles by about 8.2%.
Will 315/55R19 lift my vehicle?
Ride height changes by half the diameter difference: +1.24 inches of ground clearance at the axle.

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