285/70R17 vs 315/70R17

315/70R17 is 1.7" taller than 285/70R17 (5.1%)

Diameter difference+5.06%diameter 32.71" → 34.36"
285/70R17315/70R17
285/70R17315/70R17Difference
Overall diameter32.71"34.36"+1.65"
Section width11.22"12.40"+1.18"
Sidewall height7.85"8.68"+0.83"
Circumference102.8"108.0"+5.2"
Revolutions per mile617587−30
Wheel diameter17"17"±0"

Speedometer

ShowsActualDiff
30 mph31.5 mph+1.5
45 mph47.3 mph+2.3
60 mph63.0 mph+3.0
70 mph73.5 mph+3.5
80 mph84.0 mph+4.0

Gear ratio to match

CurrentEquivalent
3.423.59
3.553.73
3.733.92
4.104.31

315/70R17 is 1.65" taller than 285/70R17, a +5.06% change in diameter. That is more than the 3% many tire shops use as a limit, so plan on recalibrating the speedometer and checking ABS and stability control.

Ground clearance changes by 0.83" (half the diameter change), and the tire needs 0.83" more room above it.

315/70R17 is 1.18" wider. On the same wheel offset about half of that, 0.59", moves toward the suspension and half toward the fender.

Both fit a 17" wheel; the sidewall is 0.83" taller on 315/70R17.

Details: 285/70R17 in inches · 315/70R17 in inches · change sizes in the calculator

FAQ

What is the difference between 285/70R17 and 315/70R17?

315/70R17 is 1.65" taller (+5.06%) and 1.18" wider than 285/70R17.

Will 315/70R17 change my speedometer?

Yes, by +5.06%. When the speedometer shows 60 mph you would be going 63.0 mph.

Can I replace 285/70R17 with 315/70R17?

It is a +5.1% diameter change, larger than the common 3% guideline, so check clearance and plan to recalibrate.