Tire Size Box

315/45R22 vs 315/55R22

315/55R22 compared with 315/45R22

+7.5% diameter, 0.0" width

315/55R22 is 35.64" tall vs 33.16". More than the 3% rule of thumb, so check carefully before switching.

33.2"22" rim5.6"12.4" wide
315/45R22 (solid) compared with 315/55R22 (dashed outline), drawn to scale

With 315/55R22 tires, when your speedometer says 60 mph you are really going

64.5 mph

315/55R22 is +2.48 inches (+7.5%) in overall diameter. That is more than the 3% most shops and makers recommend.

315/45R22315/55R22Difference%
Overall diameter33.16"35.64"+2.48"+7.5%
Section width12.40"12.40"0.00"0.0%
Sidewall height5.58"6.82"+1.24"+22.2%
Circumference104.18"111.97"+7.79"+7.5%
Revolutions per mile608.2565.9−42.3−7.0%

Speedometer difference

If your vehicle came with 315/45R22 and you fit 315/55R22, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.5 mph+1.5 mph
30 mph32.2 mph+2.2 mph
40 mph43.0 mph+3.0 mph
50 mph53.7 mph+3.7 mph
60 mph64.5 mph+4.5 mph
65 mph69.9 mph+4.9 mph
70 mph75.2 mph+5.2 mph
75 mph80.6 mph+5.6 mph
80 mph86.0 mph+6.0 mph

Each size on its own

Questions

Which is bigger, 315/45R22 or 315/55R22?
315/55R22 is taller by 2.48 inches (35.64" vs 33.16"). 315/45R22 is the same width.
Can I replace 315/45R22 with 315/55R22?
It is not recommended without checking carefully. The diameter difference is +7.5%, 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 315/55R22 change my speedometer?
When your speedometer reads 60 mph with 315/55R22 fitted (calibrated for 315/45R22), your real speed is 64.5 mph. Your odometer will under-count miles by about 7.5%.
Will 315/55R22 lift my vehicle?
Ride height changes by half the diameter difference: +1.24 inches of ground clearance at the axle.

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