When we’re shopping for tires, understanding tire size measurements can feel like decoding a foreign language. The 315/70R17 tire size is particularly popular among truck and SUV owners, but what do these numbers actually mean in inches?
We’ve all been there – staring at tire sidewalls wondering if we’re making the right choice for our vehicle. The 315/70R17 designation tells us crucial information about width, sidewall height, and rim diameter that directly impacts our vehicle’s performance, fuel economy, and overall driving experience.
Converting these metric measurements to inches isn’t just about satisfying curiosity – it’s essential for ensuring proper fitment, understanding clearance requirements, and making informed decisions about our vehicle’s setup. Whether you’re upgrading your truck’s stance or replacing worn tires, knowing the exact dimensions in inches helps us avoid costly mistakes and optimize our ride.
Understanding 315 70 R17 Tire Size Specifications
The 315/70R17 tire size contains three distinct measurements that determine the tire’s physical dimensions and compatibility. Each number in this designation serves a exact purpose in defining how the tire fits your vehicle and performs on the road.
Breaking Down the Numbers
The first number, 315, represents the tire’s section width measured in millimeters from sidewall to sidewall. This measurement translates to approximately 12.4 inches when we convert from metric to imperial units. The second number, 70, indicates the aspect ratio or sidewall height as a percentage of the tire’s width. Finally, the letter R stands for radial construction, while 17 designates the wheel diameter in inches that this tire fits.
| Measurement | Value | Inches Equivalent |
|---|---|---|
| Section Width | 315mm | 12.4 inches |
| Aspect Ratio | 70% | 8.68 inches (sidewall height) |
| Wheel Diameter | R17 | 17 inches |
| Overall Diameter | 658mm | 25.9 inches |
What Each Measurement Represents
Section width determines the tire’s contact patch with the road surface and affects traction, handling, and fuel economy. A 315mm width provides substantial grip for trucks and SUVs while maintaining stability during cornering and braking. Aspect ratio directly influences ride comfort and handling characteristics since a 70% ratio creates a sidewall height of 8.68 inches. This moderate sidewall height balances comfort with responsive steering feedback.
Radial construction means the tire’s internal cords run perpendicular to the direction of travel, providing better fuel efficiency and longer tread life compared to bias ply tires. The 17 inch wheel diameter specification ensures proper fitment on compatible rims and affects the tire’s overall diameter of 25.9 inches. Overall diameter impacts speedometer accuracy, ground clearance, and gear ratios in your vehicle’s drivetrain.
Converting 315 70 R17 to Inches
Converting the 315/70R17 tire size from metric to imperial measurements provides precise dimensions needed for proper vehicle fitment and performance calculations. We’ll break down each component of this tire size to show you the exact inch measurements.
Width Conversion (315mm to Inches)
The section width of 315mm converts to approximately 12.4 inches when divided by 25.4mm per inch. This measurement represents the tire’s widest point from sidewall to sidewall when mounted on the recommended rim width. Converting 315mm gives us the precise width measurement: 315 ÷ 25.4 = 12.4 inches.
Tire manufacturers design the 315mm width to provide optimal contact patch for traction and handling characteristics. The 12.4-inch width fits wheel widths ranging from 8 to 10.5 inches for passenger tires and 8 to 11 inches for light truck applications.
Sidewall Height Calculation
The sidewall height equals 70% of the section width, calculated as 12.4 inches × 0.70 = 8.7 inches. This aspect ratio of 70 creates a sidewall that’s 8.7 inches tall from the rim to the tread surface. Lower aspect ratios provide better handling response while higher ratios like 70 offer improved ride comfort over rough surfaces.
Calculating the sidewall height accurately affects ground clearance measurements and overall vehicle stance. The 8.7-inch sidewall height contributes significantly to the tire’s overall diameter and impacts speedometer calibration.
Overall Diameter in Inches
The overall diameter totals 34.4 inches when combining the 17-inch wheel diameter with both sidewalls. We calculate this by adding the wheel diameter (17 inches) plus twice the sidewall height (8.7 inches × 2 = 17.4 inches). The complete formula shows: 17 + 17.4 = 34.4 inches total diameter.
| Parameter | Value in Inches |
|---|---|
| Section Width | 12.4 |
| Sidewall Height | 8.7 |
| Overall Diameter | 34.4 |
| Wheel Diameter | 17 |
| Circumference | 107.9 |
This 34.4-inch overall diameter creates a circumference of 107.9 inches and results in 587 revolutions per mile. The diameter measurement directly affects speedometer accuracy and gear ratio calculations for your vehicle’s performance characteristics.
Tire Dimensions and Performance Characteristics
The 315/70R17 tire’s exact dimensions create measurable effects on vehicle performance and driving dynamics. These characteristics directly influence how our vehicles handle various road conditions and terrains.
Tread Width Impact on Handling
The 12.4-inch section width of 315/70R17 tires creates a larger contact patch with the road surface compared to narrower alternatives. This expanded contact area delivers superior dry traction through increased rubber-to-road interface, improving cornering stability and braking performance on paved surfaces.
Wider tires like the 315/70R17 excel in dry conditions but face challenges in wet weather scenarios. The broader tread pattern can reduce the tire’s ability to cut through standing water, potentially increasing hydroplaning risks during heavy rainfall. Snow performance also diminishes as the wider contact patch struggles to penetrate through snow layers compared to narrower tire options.
Off-road handling benefits significantly from the 315/70R17’s width when traversing sand, loose dirt, and rocky terrain. The increased surface area distributes vehicle weight more effectively, reducing ground pressure and improving flotation over soft surfaces.
Sidewall Height Effects on Ride Quality
The 8.7-inch sidewall height of 315/70R17 tires provides substantial cushioning between the wheel and road surface. This generous sidewall dimension absorbs impact forces from potholes, road debris, and uneven surfaces more effectively than lower-profile alternatives.
Ride comfort improves considerably with the taller sidewall design, as the increased air volume and rubber flexibility dampen vibrations before they reach the vehicle’s suspension system. Highway driving becomes notably smoother, with reduced road noise transmission through the tire structure.
Sidewall durability presents both advantages and concerns with the 8.7-inch height specification. The additional rubber thickness offers better protection against punctures from sharp rocks and debris during off-road adventures. But, the increased sidewall flex during aggressive cornering can generate excessive heat buildup, potentially leading to premature wear or failure under extreme driving conditions.
The taller sidewall profile also affects steering response characteristics, creating a slight delay between steering input and tire reaction compared to lower-profile options. This trade-off between comfort and precision becomes particularly noticeable during spirited driving or emergency maneuvers.
Popular Vehicle Applications for 315 70 R17 Tires
The 315/70R17 tire size finds its most common applications in heavy-duty vehicles that require enhanced load-carrying capacity and versatile performance capabilities. These tires excel in demanding environments where both on-road comfort and off-road capability are essential.
Pickup Trucks and SUVs
Large capacity pickup trucks represent the primary application for 315/70R17 tires due to their exceptional load-carrying ability and robust construction. Ford F-150s, Chevrolet Silverados, and Ram 1500s frequently use this tire size for improved hauling performance and enhanced ground clearance.
SUVs benefit from the balanced performance characteristics that 315/70R17 tires provide, delivering optimal comfort for daily commuting while maintaining capability for weekend adventures. Vehicles like the Toyota 4Runner, Jeep Wrangler, and Ford Bronco commonly feature this tire size as either standard equipment or popular upgrade options.
The 34.4-inch overall diameter creates additional ground clearance that pickup truck and SUV owners value for handling obstacles and improving approach angles. This increased height also contributes to better visibility and commanding road presence that many drivers prefer in these vehicle categories.
Off-Road and All-Terrain Usage
Off-road enthusiasts frequently choose 315/70R17 tires for their aggressive tread patterns and robust construction that deliver exceptional traction across diverse terrains. These tires excel on mud, rocks, and gravel surfaces through their wider 12.4-inch contact patch that distributes vehicle weight more effectively.
All-terrain applications benefit from the tire’s ability to provide reliable performance both on highways and off-road trails without requiring tire changes between different driving conditions. The 8.7-inch sidewall height offers enhanced puncture resistance during rocky terrain navigation while maintaining adequate flex for traction over uneven surfaces.
Overlanding and expedition vehicles commonly use 315/70R17 tires because they provide the durability required for extended off-road journeys while maintaining highway comfort for long-distance travel. The 587 revolutions per mile rating ensures accurate odometer readings during navigation in remote areas where precise distance tracking becomes critical for fuel planning and route management.
Comparing 315 70 R17 to Other Common Tire Sizes
We can better understand the 315/70R17’s positioning by examining how it compares to other popular tire sizes. These comparisons reveal important differences in dimensions and performance characteristics that affect vehicle dynamics.
Size Alternatives and Equivalents
35×12.50R17 serves as the closest inch-size equivalent to 315/70R17, differing primarily in overall diameter and sidewall profile. The 35×12.50R17 measures 0.6 inches taller at 35 inches compared to the 315/70R17’s 34.4-inch diameter. This height difference creates a 1.9% speedometer variance between the two sizes.
Metric to inch conversion shows 315/70R17 translates approximately to 34×12.4-17 in traditional inch sizing. Popular alternatives include 33×12.50R17 for smaller applications and 37×12.50R17 for larger setups, though these may require vehicle modifications.
| Tire Size | Section Width (in.) | Overall Diameter (in.) | Wheel Size (in.) | Sidewall Height (in.) |
|---|---|---|---|---|
| 315/70R17 | 12.4 | 34.4 | 17 | 8.7 |
| 35×12.50R17 | 12.5 | 35 | 17 | 11.5 |
| 265/70R17 | 10.4 | 31.6 | 17 | 7.3 |
265/70R17 represents a significantly smaller option, measuring 2.8 inches less in diameter and 2 inches narrower than 315/70R17. This size difference impacts ground clearance, load capacity, and overall vehicle stance.
Performance Trade-offs
Diameter advantages of 315/70R17 include increased ground clearance and improved off-road capability compared to smaller sizes like 265/70R17. Larger diameter tires reduce acceleration performance and fuel efficiency due to increased rotational mass and altered gear ratios.
Width benefits from the 12.4-inch section provide enhanced traction and handling stability across various surfaces. Wider tires generate increased road noise and rolling resistance, reducing fuel economy compared to narrower alternatives.
Compared to 265/70R17, the 315/70R17 delivers superior off-road performance through better flotation and obstacle clearance. On-road characteristics favor the smaller 265/70R17 for smoother ride quality and improved fuel efficiency.
| Feature | 315/70R17 | 35×12.50R17 | 265/70R17 |
|---|---|---|---|
| Section Width | 12.4 in. | 12.5 in. | 10.4 in. |
| Overall Diameter | 34.4 in. | 35 in. | 31.6 in. |
| Sidewall Height | 8.7 in. | 11.5 in. | 7.3 in. |
| Wheel Diameter | 17 in. | 17 in. | 17 in. |
Installation Considerations and Fitment Guidelines
Proper installation of 315/70R17 tires requires careful attention to vehicle compatibility and safety specifications. We’ve identified critical factors that determine successful fitment and optimal performance for these larger tire dimensions.
Clearance Requirements
Ensuring adequate clearance prevents tire rubbing and maintains safe vehicle operation. The 34.4-inch overall diameter and 12.4-inch width of 315/70R17 tires demand sufficient wheel well space both horizontally and vertically.
Suspension components require inspection for potential contact points during full steering lock and suspension compression. We recommend checking clearance at maximum turning radius and under full load conditions to identify any interference issues.
Larger tires often necessitate suspension lifts or fender modifications to accommodate the increased dimensions. Trimming plastic fender liners or installing aftermarket wheel well extensions may become necessary for proper fitment.
Brake components and ABS sensors need verification for adequate spacing from the tire sidewall. Insufficient clearance can cause premature wear or system malfunctions during operation.
Load Rating and Speed Rating Factors
Load rating specifications must match or exceed vehicle manufacturer requirements to safely support the vehicle’s weight capacity. Exceeding the recommended load rating can lead to tire failure and compromised safety performance.
Speed ratings indicate the maximum safe operating velocity for sustained periods without overheating or structural failure. We emphasize selecting tires with speed ratings that meet or surpass the vehicle’s intended use requirements.
Proper speed rating selection prevents overheating and blowouts while ensuring stable handling characteristics at highway speeds. Mismatched ratings can result in premature tire degradation and dangerous driving conditions.
| Recommended Specifications | 315/70R17 Requirements |
|---|---|
| Wheel Width (Passenger) | 8 – 10.5 inches |
| Wheel Width (Light Truck) | 8 – 11 inches |
| Minimum Clearance Check | Full steering lock + compression |
| Load Rating Requirement | Meets/exceeds OEM specification |
| Speed Rating Priority | Matches intended vehicle use |
Conclusion
Understanding the 315/70R17 tire dimensions empowers us to make informed decisions about our vehicle’s performance and safety. These measurements translate to real-industry impacts on everything from fuel economy to off-road capability.
Whether we’re upgrading for better traction or replacing worn tires the precise inch conversions we’ve covered ensure proper fitment and optimal performance. Remember that the 12.4-inch width 8.7-inch sidewall height and 34.4-inch overall diameter directly influence how our vehicle handles accelerates and stops.
Taking time to verify clearances and compatibility prevents costly installation issues down the road. With this knowledge we’re better equipped to choose tires that match our driving needs and vehicle specifications perfectly.
Frequently Asked Questions
What does the 315/70R17 tire size designation mean?
The 315/70R17 designation breaks down into three key measurements: 315mm section width (12.4 inches), 70% aspect ratio indicating sidewall height, and 17-inch wheel diameter. The “R” denotes radial construction. This tire has an overall diameter of 34.4 inches and provides excellent load-carrying capacity for trucks and SUVs.
How does the 315/70R17 tire size affect vehicle performance?
The 12.4-inch width creates a larger contact patch, improving traction and braking but potentially increasing hydroplaning risk. The 8.7-inch sidewall height enhances ride comfort and impact absorption while providing better puncture protection. However, the taller sidewall may cause slight delays in steering response compared to lower-profile tires.
What vehicles commonly use 315/70R17 tires?
Popular applications include heavy-duty pickup trucks like Ford F-150 and Chevrolet Silverado, as well as SUVs such as Toyota 4Runner and Jeep Wrangler. These vehicles benefit from the tire’s enhanced load-carrying capacity, improved ground clearance, and versatile performance for both daily driving and off-road adventures.
How does 315/70R17 compare to other common tire sizes?
Compared to 35×12.50R17, the 315/70R17 is slightly shorter but nearly equivalent. The 265/70R17 is significantly smaller, offering better fuel efficiency but reduced ground clearance and load capacity. The 315/70R17 provides superior off-road capabilities while maintaining reasonable highway comfort and performance.
What installation considerations are important for 315/70R17 tires?
Check clearance requirements to prevent rubbing against suspension components, fenders, or wheel wells. Verify that load and speed ratings match your vehicle’s specifications. Larger tires may require suspension lifts or fender modifications. Ensure proper wheel width compatibility and conduct thorough clearance checks before installation.
Are 315/70R17 tires good for off-road use?
Yes, 315/70R17 tires excel in off-road conditions due to their aggressive tread patterns and robust construction. The wide footprint distributes weight effectively over soft surfaces, while the tall sidewall provides impact protection. They’re popular among off-road enthusiasts and overlanding vehicles for their durability and versatile terrain performance.