introduction to 315/70R17 to Inches
Quick Answer: A 315/70R17 tire is 34.36 inches tall (about 34 3/8 in, or 2 ft 10.4 in) and 12.40 inches wide, with an 8.68-inch sidewall on a 17-inch wheel. In imperial terms it works out to roughly 34.4 x 12.4R17, and it makes about 587 revolutions per mile.
The 315/70R17 is a popular off-road truck size, but many people expect it to measure a full 35 inches. It is close, though not quite there. This guide shows you how the numbers are calculated, what every part of the code means, and how the size compares with the tires you might be choosing between.
315/70R17 Tire Size in Inches at a Glance
| Measurement | Inches | Millimeters |
|---|---|---|
| Overall diameter (height) | 34.36 in (≈ 34 3/8 in) | 872.8 mm |
| Section width | 12.40 in (≈ 12 3/8 in) | 315 mm |
| Sidewall height | 8.68 in (≈ 8 11/16 in) | 220.5 mm |
| Rim (wheel) diameter | 17 in | 431.8 mm |
| Radius (center to ground) | 17.18 in | 436.4 mm |
| Circumference | 107.95 in (≈ 9 ft) | 2,742 mm |
| Revolutions per mile | 586.9 | — |
| Revolutions per kilometer | 364.7 | — |
These are calculated nominal figures. Actual size can vary slightly by brand and tread pattern. Mud-terrain tires with deep tread often measure a few tenths of an inch taller than the math suggests.
What Does 315/70R17 Mean? The Tire Code Explained
Each part of the size code tells you something specific.
315 — Section Width
This is the tire’s width from sidewall to sidewall, in millimeters, when mounted on its recommended rim. 315 mm ÷ 25.4 = 12.40 inches.
70 — Aspect Ratio
The sidewall height is 70% of the width. 315 × 0.70 = 220.5 mm, which is 8.68 inches. A higher number means a taller, softer sidewall, which helps on rocks and rough trails.
R — Radial Construction
The internal plies run radially across the tire. Nearly every modern truck and SUV tire is radial.
17 — Rim Diameter
The tire fits a 17-inch wheel. This is the only part of the code already given in inches.
LT or P Prefix
You will often see this size written as LT315/70R17. “LT” means light truck construction, built for heavier loads and towing. A typical load index for this size is 121, meaning up to 3,197 lbs per tire.
How to Calculate 315/70R17 in Inches (Step by Step)
Here is the full math, so you can check it or repeat it for any tire size.
Step 1 – Convert width to inches:
315 ÷ 25.4 = 12.4016 in → 12.40 in
Step 2 – Find the sidewall height:
315 × 70 ÷ 100 = 220.5 mm
220.5 ÷ 25.4 = 8.6811 in → 8.68 in
Step 3 – Calculate overall diameter:
Diameter = rim + (2 × sidewall)
17 + (2 × 8.6811) = 17 + 17.3622 = 34.3622 in → 34.36 in
Step 4 – Find the circumference:
34.3622 × 3.1416 = 107.95 in
Step 5 – Find revolutions per mile:
One mile = 63,360 inches
63,360 ÷ 107.95 = 586.9 revolutions per mile
As a fraction, 34.36 inches is closest to 34 3/8 inches. In feet and inches, that is 2 feet 10.36 inches.
Is 315/70R17 a 35-Inch Tire?
Not exactly. A 315/70R17 measures 34.36 inches, so it is about 0.64 inch shorter than a true 35-inch tire. That is why it is often called a “small 35” or a “34.5-inch tire” by off-road builders.
The width also lands very close to a 35×12.50R17, which is 12.50 inches wide versus 12.40 inches. In daily driving, most people cannot tell the difference. The gap matters mainly when you are measuring fender clearance or calculating gear ratios.
315/70R17 vs Similar Tire Sizes
This table compares 315/70R17 with the sizes people most often consider alongside it.
| Tire Size | Diameter (in) | Width (in) | Sidewall (in) | Difference vs 315/70R17 |
|---|---|---|---|---|
| 265/70R17 | 31.61 | 10.43 | 7.30 | −2.76 in (−8.0%) |
| 285/70R17 | 32.71 | 11.22 | 7.85 | −1.65 in (−4.8%) |
| 33×12.50R17 | 33.00 | 12.50 | 8.00 | −1.36 in (−4.0%) |
| 295/70R17 | 33.26 | 11.61 | 8.13 | −1.10 in (−3.2%) |
| 285/75R17 | 33.83 | 11.22 | 8.42 | −0.53 in (−1.6%) |
| 305/70R17 | 33.81 | 12.01 | 8.41 | −0.55 in (−1.6%) |
| 315/70R17 | 34.36 | 12.40 | 8.68 | — |
| 35×12.50R17 | 35.00 | 12.50 | 9.00 | +0.64 in (+1.9%) |
Imperial “flotation” sizes like 33×12.50 and 35×12.50 are nominal, so real measurements vary more by brand.
315/70R17 vs 285/70R17
The 285/70R17 is a common factory size on many full-size trucks. Moving up to 315/70R17 adds about 1.65 inches of height and 1.18 inches of width. This is one of the most popular “plus-size” upgrades for trucks that came with 285s.
315/70R17 vs 35×12.50R17
These two sizes are nearly interchangeable. The 35×12.50R17 is slightly taller and wider. If clearance is tight, the 315/70R17 is the safer choice by a small margin.
Which Vehicles Use 315/70R17 Tires?
The 315/70R17 is mostly found on trucks and off-road vehicles built for trails and towing.
- Ford F-150 Raptor (2017–2020 generation) came with LT315/70R17 tires from the factory.
- Heavy-duty pickups such as the Ram 2500, Ford F-250 and Chevy Silverado 2500HD often run this size as an upgrade, usually with a leveling kit.
- Full-size half-ton trucks like the Ram 1500, F-150 and Silverado 1500 can fit it with a level or small lift.
- Jeep Wrangler and Gladiator builds often use it with a 2.5-inch lift or more.
- Toyota Tacoma, 4Runner and Tundra owners use it on lifted builds.
Fitment depends on your wheel offset, suspension and trim level. Always check before buying.
Rim Width for 315/70R17
A tire this wide needs a wide enough wheel to hold its shape. A 315/70R17 is commonly mounted on wheels between about 8.5 and 11 inches wide, with 9 to 10 inches being the most common choice. Check the tire maker’s spec sheet for the exact approved range.
Speedometer and Clearance Considerations
Switching to a taller tire changes how far your truck travels with each wheel turn. Your speedometer will read lower than your actual speed.
Speedometer Error Examples
| Upgrading From | Size Increase | Speedometer Shows | Actual Speed |
|---|---|---|---|
| 285/70R17 (32.71 in) | +5.1% | 60 mph | ≈ 63.0 mph |
| 265/70R17 (31.61 in) | +8.7% | 60 mph | ≈ 65.2 mph |
| 35×12.50R17 (35.00 in) | −1.8% | 60 mph | ≈ 58.9 mph |
Most modern trucks let you recalibrate the speedometer with an inexpensive programmer or at a dealer. This also corrects shift points and odometer readings.
Ground Clearance Gain
Only half of the diameter increase lifts the axle. Going from 285/70R17 to 315/70R17 raises your ground clearance by about 0.83 inch. Going from 265/70R17 adds about 1.38 inches.
Clearance Checklist
- Turn the steering to full lock and check for rubbing on the frame and mud flaps.
- Check the upper control arm area, especially with low-offset wheels.
- Watch for contact on the fender liners during suspension compression.
- Expect a slight drop in fuel economy and acceleration because of the extra weight.
- Consider regearing if you tow heavy loads with a big size jump.
Quick Mental Math for Any Tire Size
You can estimate a metric tire’s height in your head:
- Multiply width by aspect ratio: 315 × 0.7 ≈ 220 mm.
- Divide by 25 (close to 25.4): 220 ÷ 25 ≈ 8.8 inches of sidewall.
- Double it and add the rim: 17 + 17.6 ≈ 34.6 inches.
That quick estimate lands within a quarter inch of the exact 34.36 inches, close enough for a first check.
Common Mistakes to Avoid
- Assuming it is a true 35-inch tire. It is 34.36 inches, so don’t buy one expecting identical results to a 35×12.50.
- Reading 315 as inches. The first number is millimeters, not inches.
- Treating 70 as millimeters. It is a percentage of the width, not a measurement.
- Ignoring wheel offset. The same tire can rub on one wheel and clear on another.
- Mixing P and LT versions. Load ratings and recommended pressures differ, so match all four tires.
FAQs
How tall is a 315/70R17 tire in inches?
A 315/70R17 tire is 34.36 inches tall, which is about 34 3/8 inches or 2 feet 10.4 inches. Real-world height may be a little higher or lower depending on the brand and tread depth.
How wide is a 315/70R17 tire in inches?
The section width is 12.40 inches, or about 12 3/8 inches. The tread itself is usually a bit narrower than the overall section width.
What is 315/70R17 in standard tire sizing?
In imperial terms, 315/70R17 converts to roughly 34.4×12.4R17. It is commonly grouped with 35×12.50R17 tires, although it is slightly smaller.
Will 315/70R17 tires fit my truck without a lift?
Some heavy-duty pickups can fit them stock, while most half-ton trucks need at least a leveling kit. Wheel offset and trim matter, so check your specific setup before buying.
How many revolutions per mile does a 315/70R17 make?
A 315/70R17 makes about 587 revolutions per mile, or roughly 365 revolutions per kilometer.
Is 315/70R17 bigger than 285/75R17?
Yes. A 315/70R17 is about 0.53 inch taller and 1.18 inches wider than a 285/75R17.
Does a 315/70R17 affect gas mileage?
Usually, yes. The larger, heavier tire takes more energy to turn, so many drivers see a small drop in fuel economy, especially with aggressive mud-terrain tread.
Final Thoughts
A 315/70R17 tire measures 34.36 inches tall, 12.40 inches wide and has an 8.68-inch sidewall on a 17-inch wheel. It sits just under a true 35-inch tire, which makes it a favorite for truck owners who want an aggressive look and better clearance without major modifications. Before you buy, check your wheel width, offset and suspension, and plan to recalibrate your speedometer if you are moving up from a smaller size.
Also read How Many Inches Is 9 Feet? Exact Answer, Formula & Chart
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