Tire RulerWhat changes when you switch to 315/70R17
- Height: +0.53″ (+1.6%), so ground clearance at the axle goes up 0.27″.
- Width: +1.18″ (30 mm). Check inner clearance to the suspension and frame, and the fender liner at full lock.
- Sidewall: +0.27″. A taller sidewall rides a bit softer and protects the wheel off-road.
- Revolutions per mile: 596 → 587. Your gears act about 1.6% taller; at 65 mph in a 0.69 top gear with 3.73s, that’s 1,662 → 1,636 RPM.
Sizes are theoretical, from the sidewall code. The same size can differ by a few tenths of an inch between brands and tread patterns; check the maker’s spec sheet for the exact model.
Other comparisons
Frequently asked questions
How much bigger is 315/70R17 than 285/75R17?
315/70R17 is 0.53 inches (1.6%) taller and 1.18 inches wider: 34.4" × 12.4" versus 33.8" × 11.2".
Will 315/70R17 change my speedometer?
Yes, by 1.6%. Going from 285/75R17 to 315/70R17, an indicated 60 mph is about 60.9 mph.
Can I replace 285/75R17 with 315/70R17?
Often, yes: the height difference is within the ±3% most tire shops accept. Both fit a 17" wheel; confirm the rim width, load index and clearance for your vehicle.
Do I need to regear going from 285/75R17 to 315/70R17?
Usually not for a 1.6% change. With 3.73 gears, the 315/70R17 acts like 3.67.