For the full breakdown, see our best 315/70R17 All Terrain Tires guide.
The number hiding in that tire-size code tells you more than the height, though. The 315/70R17 designation is a formula: the 315 is the width in millimeters, the 70 is the aspect ratio, and the 17 is the wheel diameter in inches.
That makes 315/70R17 a tall, wide tire commonly fitted to heavy-duty trucks, SUVs, and off-road builds. But the mounted height you actually get depends on the specific tire model and your truck’s setup.
The Numbers Behind The 315/70R17 Size
Here’s how the three parts of the size code break down in practical terms:
- 315 — the nominal section width in millimeters, or about 12.4 inches. It measures the widest point of the tire when mounted, not tread width.
- 70 — the aspect ratio; sidewall height is roughly 70% of the section width.
- R17 — radial construction, designed to fit a 17-inch wheel.
Real-World Heights Vary By Tire Model
The 34.4-inch figure is a useful baseline, but it’s not a universal guarantee. Tire makers measure slightly differently, and actual mounted diameter shifts with rim width, inflation pressure, and tread design. Model-specific listings reveal small but real differences:
The differences matter for speedometer accuracy and suspension clearance, but a fraction of an inch rarely changes your buying decision. For trucks needing aggressive off-road rubber in this size, our tested roundup of the best 315/70R17 all-terrain tires breaks down which models fit tight clearance and heavy loads best.
Rim Width And Load Ratings Matter Too
The same 315/70R17 tire can sit taller or shorter depending on the wheel it mounts to. Recommended rim widths vary by model: some size guides call for 8–11 inches, while others specify 8–10.5 or 8–11 inches depending on the tire. A wider rim spreads the tire’s footprint and reduces sidewall bulge, which can lower the mounted height slightly.
Load and speed ratings also differ between versions of the same size. These figures reflect the tire’s internal construction and directly affect how much weight your truck can haul safely.
| Tire Model | Diameter | Max Load (Front/Rear) |
|---|---|---|
| Nitto Ridge Grappler E | 34.41 in | 3,195 / 2,910 lb |
| BFG All-Terrain KO2 C | 34.4 in | 2,535 / 2,335 lb |
| BFG All-Terrain KO3 F | 34.4 in | 3,970 / 3,640 lb |
Will They Fit Your Truck?
Before you buy, verify two things. First, check the clearance in your wheel wells at full suspension compression and full steering lock. Second, confirm your current rim width falls within the tire’s recommended range — mounting on a rim that’s too narrow can cause premature wear.
Also expect a minor speedometer shift. A 315/70R17 is taller than many factory tires, so your speedometer will read slightly slower than your actual speed. A quick GPS check after mounting is the easiest way to know the real difference.
References & Sources
- Tiresize.com. “315/70R17 Tire Size Calculator.” Provides the standard diameter, width, and circumference figures for this size.
- 1010tires.com. “Tire Size Calculator 315/70R17.” Confirms the calculated 34.4-inch diameter and sidewall height.
- Tiresize.com. “Nitto Ridge Grappler 315/70R17 Specs.” Source for model-specific diameter, load rating, and revs-per-mile figures.