Tire Size Box

315/55R19 vs 315/65R19

315/65R19 compared with 315/55R19

+7.6% diameter, 0.0" width

315/65R19 is 35.12" tall vs 32.64". More than the 3% rule of thumb, so check carefully before switching.

32.6"19" rim6.8"12.4" wide
315/55R19 (solid) compared with 315/65R19 (dashed outline), drawn to scale

With 315/65R19 tires, when your speedometer says 60 mph you are really going

64.6 mph

315/65R19 is +2.48 inches (+7.6%) in overall diameter. That is more than the 3% most shops and makers recommend.

315/55R19315/65R19Difference%
Overall diameter32.64"35.12"+2.48"+7.6%
Section width12.40"12.40"0.00"0.0%
Sidewall height6.82"8.06"+1.24"+18.2%
Circumference102.55"110.34"+7.79"+7.6%
Revolutions per mile617.9574.2−43.6−7.1%

Speedometer difference

If your vehicle came with 315/55R19 and you fit 315/65R19, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.5 mph+1.5 mph
30 mph32.3 mph+2.3 mph
40 mph43.0 mph+3.0 mph
50 mph53.8 mph+3.8 mph
60 mph64.6 mph+4.6 mph
65 mph69.9 mph+4.9 mph
70 mph75.3 mph+5.3 mph
75 mph80.7 mph+5.7 mph
80 mph86.1 mph+6.1 mph

Each size on its own

Questions

Which is bigger, 315/55R19 or 315/65R19?
315/65R19 is taller by 2.48 inches (35.12" vs 32.64"). 315/55R19 is the same width.
Can I replace 315/55R19 with 315/65R19?
It is not recommended without checking carefully. The diameter difference is +7.6%, 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 315/65R19 change my speedometer?
When your speedometer reads 60 mph with 315/65R19 fitted (calibrated for 315/55R19), your real speed is 64.6 mph. Your odometer will under-count miles by about 7.6%.
Will 315/65R19 lift my vehicle?
Ride height changes by half the diameter difference: +1.24 inches of ground clearance at the axle.

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