What Size Tire Is 315 70R17? | Inches, Fit, And Math

A 315/70R17 tire is about 34.4 inches tall, 12.4 inches wide, and built for a 17-inch wheel.

If you’re staring at 315 70R17 and trying to turn that code into a real size, the answer is pretty simple once you break the numbers apart. This tire is a wide, tall light-truck size that lands close to a 34-inch tire, though many drivers round it up and talk about it like a “34” or “35” depending on the brand and tread shape.

It affects clearance, gearing feel, speedometer readings, wheel choice, and how your truck sits on the road or trail. If you want the plain-English version, 315 means the tire is 315 millimeters wide, 70 is the sidewall height as a percent of that width, and 17 is the wheel diameter in inches.

315/70R17 Tire Size Dimensions And Fit Notes

The quick math gives you the numbers most truck owners want. A 315/70R17 has a sidewall height of 220.5 millimeters, which works out to about 8.7 inches. Double that sidewall, add the 17-inch wheel, and the overall tire diameter lands at about 34.4 inches.

Width is the other half of the story. The 315 in the size code converts to about 12.4 inches of section width. Section width is measured at the sidewalls on a specified measuring wheel, so the tread itself is often a bit narrower. That’s why two tires with the same printed size can look a touch different once mounted.

• Section width: 315 mm or 12.4 inches
• Sidewall height: 220.5 mm or 8.7 inches
• Overall diameter: 34.4 inches
• Circumference: about 108.0 inches
• Revolutions per mile: about 587

What Each Part Of 315 70R17 Means

The code reads from left to right. The first number is width in millimeters. The second number is the aspect ratio, which tells you the sidewall height compared with the width. The R means radial construction, which is the standard on modern road tires. The last number is the wheel diameter, so this tire mounts on a 17-inch rim.

How Big A 315/70R17 Looks In Real Life

On paper, 34.4 inches may sound close to any other big all-terrain size. On a truck, it has a stout sidewall and a broad footprint that fills the wheel well in a hurry. Compared with a stock tire on many midsize or half-ton trucks, a 315/70R17 can add a lot of visual bulk even before you change the suspension.

The sidewall is a big piece of that look. At about 8.7 inches tall, the tire has enough sidewall to flex off-road and still keep that full, meaty stance people chase with 17-inch wheels.

You’ll also notice the width when the tire is turned lock to lock. A 12.4-inch section width can sit close to the upper control arm, sway bar, pinch weld, mud flap, or fender liner, depending on wheel offset and the shape of the tire shoulder.

Size Mark	What It Tells You	315/70R17 Result
315	Section width in millimeters	315 mm / 12.4 in
70	Sidewall height as a percent of width	220.5 mm / 8.7 in
R	Radial tire construction	Radial casing
17	Wheel diameter in inches	17-inch rim
Overall diameter	Wheel diameter plus two sidewalls	34.4 in
Circumference	Distance in one full turn	108.0 in
Revs per mile	How many turns the tire makes in one mile	About 587
Wheel fit	Rim diameter the tire is built for	17-inch wheel

That reading method matches Goodyear’s tire size definitions, and the raw dimension formula lines up with Tire Rack’s tire dimension method.

Will A 315/70R17 Fit Your Truck Without Rubbing?

That depends on the truck, the wheel, and the tire brand. The size itself is large enough that stock clearance can get tight in a hurry. Some full-size trucks can swallow it with mild tweaks. Many midsize trucks need trimming, a level, a lift, wheel changes, or a mix of all four.

Height is only half the fitment puzzle. Width and wheel offset usually decide where rubbing shows up first. A wheel that pushes the tire farther out can clear the frame but catch the fender or mud flap. A wheel that tucks the tire inboard can do the opposite and run close to suspension parts.

Checks Worth Making Before You Order

• Measure current tire clearance at full lock and full compression.
• Check the wheel width and offset, not just the rim diameter.
• Measure the upper control arm gap on the inside shoulder.
• Inspect the liner, pinch weld, and mud flap area in front of the tire.
• Check spare-tire space if you want a matching full-size spare.

A second detail many buyers miss is that tire brands don’t all run the same. One 315/70R17 mud-terrain may stand taller and wider than an all-terrain in the same printed size. Tread blocks, shoulder shape, and casing design can shift the real mounted dimensions enough to matter when your clearance is already tight.

What Changes When You Switch To 315/70R17

A tire this large changes how the truck feels. You gain ground clearance from the added diameter, though only half the diameter increase shows up under the axle. If you move from a 32.0-inch tire to a 34.4-inch tire, axle clearance rises by about 1.2 inches.

Since the tire travels farther with each turn, the truck is moving faster than the stock reading suggests unless the vehicle is recalibrated. That can also soften acceleration a bit and make the transmission hunt more often on hills if the truck already has tall gearing.

There’s a ride trade-off too. The larger sidewall can smooth out broken pavement and trail chatter, but the wider, heavier tire can dull steering response and add braking distance. Fuel economy can dip once you add more rotating weight and rolling resistance.

Tire Size	Approx. Diameter	What Changes From 315/70R17
285/70R17	32.7 in	Shorter and narrower, easier fit on many trucks
295/70R17	33.3 in	Closer in height, less section width
35×12.50R17	About 34.5 to 35.0 in	Near match in width, often a touch taller
315/75R17	35.6 in	Taller step up with more clearance demand

Where Drivers Usually Notice The Difference

Most people notice three things right away: stance, clearance, and steering feel. The truck sits fuller in the wheel well, obstacles under the axle get easier to clear, and the steering can feel slower or heavier at parking-lot speeds. If the tire is also more aggressive, road noise can rise a notch.

• Upsides: more sidewall, more axle clearance, fuller stance, wider footprint
• Trade-offs: more weight, more rubbing risk, speedometer error, mileage drop on many builds

Is 315/70R17 The Same As A 35?

Not exactly. 315/70R17 comes out to about 34.4 inches, so it falls shy of a true 35-inch measurement. In day-to-day truck talk, people still lump it near the 35-inch crowd because the difference is small enough that the same fitment issues often show up.

That said, the printed number on the sidewall is not the whole story. One tire brand may measure close to 34.6 inches when mounted and inflated, while another can land lower. Wear, air pressure, load, and wheel width also nudge the real-world height a bit.

Wheel Pairing And Buying Notes

This size is built for a 17-inch wheel, though rim width still matters for the tire’s shape and clearance. A narrower wheel can pull the sidewalls inward and change how the shoulder sits. A wider wheel can flatten the tread and move the sidewall closer to fenders and suspension pieces. Before you buy, read the spec sheet for the exact tire model rather than trusting the size code alone.

If you’re comparing options, don’t stop at the size stamp. Check load rating, tire weight, tread type, and measured dimensions on the brand’s data sheet. Two tires with the same 315/70R17 label can drive quite differently once mounted on the same truck.

What Size Tire Is 315 70R17? Plain-English Take

In plain English, this is a wide 34-inch-class tire for a 17-inch wheel. The sidewall is tall enough for off-road use, the section width is broad enough to change fitment on many trucks, and the total height sits just under the line where people start calling a tire a true 35.

If you only need the raw numbers, stick with 34.4 inches tall and 12.4 inches wide. If you need to know whether it will fit, treat those numbers as the start of the job, then match them against your truck’s wheel width, offset, suspension, and available clearance before you order.