Tire Size Box

295/70R17 vs 315/70R17

315/70R17 compared with 295/70R17

+3.3% diameter, +0.8" width

315/70R17 is 34.36" tall vs 33.26". More than the 3% rule of thumb, so check carefully before switching.

33.3"17" rim8.1"11.6" wide
295/70R17 (solid) compared with 315/70R17 (dashed outline), drawn to scale

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

62.0 mph

315/70R17 is +1.10 inches (+3.3%) in overall diameter. That is more than the 3% most shops and makers recommend.

295/70R17315/70R17Difference%
Overall diameter33.26"34.36"+1.10"+3.3%
Section width11.61"12.40"+0.79"+6.8%
Sidewall height8.13"8.68"+0.55"+6.8%
Circumference104.49"107.95"+3.46"+3.3%
Revolutions per mile606.4586.9−19.5−3.2%

Speedometer difference

If your vehicle came with 295/70R17 and you fit 315/70R17, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.7 mph+0.7 mph
30 mph31.0 mph+1.0 mph
40 mph41.3 mph+1.3 mph
50 mph51.7 mph+1.7 mph
60 mph62.0 mph+2.0 mph
65 mph67.2 mph+2.2 mph
70 mph72.3 mph+2.3 mph
75 mph77.5 mph+2.5 mph
80 mph82.7 mph+2.7 mph

Each size on its own

Questions

Which is bigger, 295/70R17 or 315/70R17?
315/70R17 is taller by 1.10 inches (34.36" vs 33.26"). 315/70R17 is wider by 0.79 inches.
Can I replace 295/70R17 with 315/70R17?
It is not recommended without checking carefully. The diameter difference is +3.3%, 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 295/70R17), your real speed is 62.0 mph. Your odometer will under-count miles by about 3.3%.
Will 315/70R17 lift my vehicle?
Ride height changes by half the diameter difference: +0.55 inches of ground clearance at the axle.

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