Tire Size Box

295/75R17 vs 315/75R17

315/75R17 compared with 295/75R17

+3.4% diameter, +0.8" width

315/75R17 is 35.60" tall vs 34.42". More than the 3% rule of thumb, so check carefully before switching.

34.4"17" rim8.7"11.6" wide
295/75R17 (solid) compared with 315/75R17 (dashed outline), drawn to scale

With 315/75R17 tires, when your speedometer says 60 mph you are really going

62.1 mph

315/75R17 is +1.18 inches (+3.4%) in overall diameter. That is more than the 3% most shops and makers recommend.

295/75R17315/75R17Difference%
Overall diameter34.42"35.60"+1.18"+3.4%
Section width11.61"12.40"+0.79"+6.8%
Sidewall height8.71"9.30"+0.59"+6.8%
Circumference108.14"111.85"+3.71"+3.4%
Revolutions per mile585.9566.5−19.4−3.3%

Speedometer difference

If your vehicle came with 295/75R17 and you fit 315/75R17, 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 mph41.4 mph+1.4 mph
50 mph51.7 mph+1.7 mph
60 mph62.1 mph+2.1 mph
65 mph67.2 mph+2.2 mph
70 mph72.4 mph+2.4 mph
75 mph77.6 mph+2.6 mph
80 mph82.7 mph+2.7 mph

Each size on its own

Questions

Which is bigger, 295/75R17 or 315/75R17?
315/75R17 is taller by 1.18 inches (35.60" vs 34.42"). 315/75R17 is wider by 0.79 inches.
Can I replace 295/75R17 with 315/75R17?
It is not recommended without checking carefully. The diameter difference is +3.4%, 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 315/75R17 change my speedometer?
When your speedometer reads 60 mph with 315/75R17 fitted (calibrated for 295/75R17), your real speed is 62.1 mph. Your odometer will under-count miles by about 3.4%.
Will 315/75R17 lift my vehicle?
Ride height changes by half the diameter difference: +0.59 inches of ground clearance at the axle.

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