285/75R17 vs 315/70R17

315/70R17 is 0.5" taller than 285/75R17 (1.6%)

Diameter difference+1.57%diameter 33.83" → 34.36"
285/75R17315/70R17
285/75R17315/70R17Difference
Overall diameter33.83"34.36"+0.53"
Section width11.22"12.40"+1.18"
Sidewall height8.42"8.68"+0.27"
Circumference106.3"108.0"+1.7"
Revolutions per mile596587−9
Wheel diameter17"17"±0"

Speedometer

ShowsActualDiff
30 mph30.5 mph+0.5
45 mph45.7 mph+0.7
60 mph60.9 mph+0.9
70 mph71.1 mph+1.1
80 mph81.3 mph+1.3

Gear ratio to match

CurrentEquivalent
3.423.47
3.553.61
3.733.79
4.104.16

315/70R17 is 0.53" taller than 285/75R17, a +1.57% change in diameter, inside the 3% range most shops treat as a safe swap.

Ground clearance changes by 0.27" (half the diameter change), and the tire needs 0.27" 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 0.27" taller on 315/70R17.

Details: 285/75R17 in inches · 315/70R17 in inches · change sizes in the calculator

FAQ

What is the difference between 285/75R17 and 315/70R17?

315/70R17 is 0.53" taller (+1.57%) and 1.18" wider than 285/75R17.

Will 315/70R17 change my speedometer?

Yes, by +1.57%. When the speedometer shows 60 mph you would be going 60.9 mph.

Can I replace 285/75R17 with 315/70R17?

Often yes: the diameter change of +1.6% is within the common 3% guideline. Check the load index, speed rating and clearance.