285/70R17 vs 315/70R17 — Tire Size Comparison
A 315/70R17 is 34.36" tall and 12.4" wide. A 285/70R17 is 32.71" tall and 11.22" wide. The 315/70R17 is +1.65" (+5.06%) in diameter, adds about 0.83" of ride height, and at an indicated 60 mph your actual speed becomes about 63 mph.
Current tire on your vehicle now
New tire you are considering
Full comparison
| Measurement | 285/70R17 | 315/70R17 |
|---|---|---|
| Overall diameter | 32.71" | 34.36" +1.65" (+5.06%) |
| Width | 11.22" | 12.4" +1.18" |
| Sidewall height | 7.85" | 8.68" +0.83" |
| Circumference | 102.8" | 108" +5.2" |
| Revolutions / mile | 617 | 587 -30 revs |
| Ride height change | — | +0.83" |
Speedometer effect
Assuming your speedometer was accurate on the current tire, here is what changes. Bigger tires make the speedometer read low — you travel faster than it shows.
| Speedometer shows | 20 mph | 30 mph | 40 mph | 50 mph | 60 mph | 70 mph | 80 mph |
|---|---|---|---|---|---|---|---|
| Actual speed | 21 | 31.5 | 42 | 52.5 | 63 | 73.5 | 84 |
What else changes
Odometer: it under-records by about 5.06%, the same error as the speedometer. When the clock shows 100,000 miles you have really covered about 105,100 miles — count service intervals and lease mileage by the real figure.
Gearing & feel: effectively 5.06% taller gearing. The truck pulls a touch lazier from a stop and works harder towing; at this size of change most drivers notice it mainly on hills or with a trailer.
Fuel economy: a taller, heavier tire usually costs a little fuel — through its weight, tread pattern and the taller gearing above. That part depends on the specific tire model, so no honest figure comes from the size code alone.
Before you buy: fitment checklist
- Wheel diameter:SAME RIMBoth sizes have a 17" bead-seat diameter, so the wheel diameter matches and no new wheels are needed for diameter. That says nothing about wheel width — see the rim-width check below.
- Diameter change:DIAMETERDiameter changes 5.06% — beyond the ±3% rule of thumb installers commonly cite. Expect speedometer, gearing and clearance effects to matter. The ±3% figure is a guideline, not a safety standard.
- Clearance:WIDTHThe new tire is 30 mm wider — check inner clearance at full steering lock and full suspension travel.
- Rim width:CHECKConfirm the new size's approved rim-width range (from the tire maker) includes your wheel's width.
- Load & speed:CHECKThe new tire's load index and speed rating must meet or exceed your vehicle's placard (driver's door jamb).
- Warranty & inspection:NOTERunning a non-stock size can complicate warranty claims on related parts, and a few places check tire size at inspection. If either matters to you, check your vehicle's terms first.
This is a size comparison, not a fitment guarantee. Clearance depends on your vehicle's suspension, wheel offset and alignment — the checklist above covers what to verify.
Will the 315/70R17 rub on a stock vehicle?
Rubbing is the question size math alone cannot settle — it depends on your vehicle's wheel wells, wheel offset and suspension. What the numbers here can tell you is how much less room you will have:
- Top and ends: the 315/70R17 is 1.65" taller, so its tread sits about 0.83" closer to the top of the wheel well and to the front and back edges when steering.
- Sides: it is 30 mm wider. On the same wheels, roughly half of a width change goes inward (toward suspension and frame) and half outward (toward the fender).
- When it happens: rubbing almost always shows up at full steering lock, under suspension compression — bumps, driveways, off-road — or with snow chains, not rolling straight on flat road.
Check before you buy: park with the wheels turned full lock each way and measure your tightest gaps — inner sidewall to suspension, tread top to the fender liner. If those gaps are smaller than the changes above, expect contact. A specific tire model can also measure a few tenths of an inch off nominal. Full guide: will bigger tires rub?
More comparisons with these sizes
How much bigger is a 315/70R17 than a 285/70R17?
Taller by 1.65" in diameter (5.06%), 1.18" wider, with a 0.83" taller sidewall. Revolutions per mile go from 617 to 587.
Can I switch from 285/70R17 to 315/70R17 on the same wheels?
Both sizes mount on a 17" wheel, so the wheel diameter matches. You still need your wheel's width inside the 315/70R17's approved rim-width range, a load index and speed rating at least equal to your door-jamb placard, and clearance at full lock — see the checklist above.
Will the speedometer be off?
Yes, by about 5.06%. At an indicated 60 mph you are actually doing about 63 mph on the 315/70R17.
Nominal geometry — method. Last verified November 12, 2026.