Tire Size Box

315/60R17 vs 315/70R17

315/70R17 compared with 315/60R17

+7.8% diameter, 0.0" width

315/70R17 is 34.36" tall vs 31.88". More than the 3% rule of thumb, so check carefully before switching.

31.9"17" rim7.4"12.4" wide
315/60R17 (solid) compared with 315/70R17 (dashed outline), drawn to scale

With 315/70R17 tires, when your speedometer says 60 mph you are really going

64.7 mph

315/70R17 is +2.48 inches (+7.8%) in overall diameter. That is more than the 3% most shops and makers recommend.

315/60R17315/70R17Difference%
Overall diameter31.88"34.36"+2.48"+7.8%
Section width12.40"12.40"0.00"0.0%
Sidewall height7.44"8.68"+1.24"+16.7%
Circumference100.16"107.95"+7.79"+7.8%
Revolutions per mile632.6586.9−45.7−7.2%

Speedometer difference

If your vehicle came with 315/60R17 and you fit 315/70R17, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.6 mph+1.6 mph
30 mph32.3 mph+2.3 mph
40 mph43.1 mph+3.1 mph
50 mph53.9 mph+3.9 mph
60 mph64.7 mph+4.7 mph
65 mph70.1 mph+5.1 mph
70 mph75.4 mph+5.4 mph
75 mph80.8 mph+5.8 mph
80 mph86.2 mph+6.2 mph

Each size on its own

Questions

Which is bigger, 315/60R17 or 315/70R17?
315/70R17 is taller by 2.48 inches (34.36" vs 31.88"). 315/60R17 is the same width.
Can I replace 315/60R17 with 315/70R17?
It is not recommended without checking carefully. The diameter difference is +7.8%, 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 315/70R17 change my speedometer?
When your speedometer reads 60 mph with 315/70R17 fitted (calibrated for 315/60R17), your real speed is 64.7 mph. Your odometer will under-count miles by about 7.8%.
Will 315/70R17 lift my vehicle?
Ride height changes by half the diameter difference: +1.24 inches of ground clearance at the axle.

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