Quick Answer Box
315/70R17 Tire Size Converted to Inches:
- Overall Diameter: 34.36 inches (≈ 34 3/8 in) — 2.86 feet
- Section Width: 12.40 inches (≈ 12 3/8 in) — 1.03 feet
- Sidewall Height: 8.68 inches (≈ 8 11/16 in)
- Formula: (315mm ÷ 25.4) = width in inches → width × 0.70 × 2 = total sidewall height → + 17in rim = 34.36 in overall diameter
What is 315/70R17 in Inches?
315/70R17 is a metric tire size that converts to 34.36 inches tall and 12.40 inches wide in imperial units. The “315” is the section width in millimeters (metric), the “70” is the aspect ratio (sidewall height as a percent of width), and the “17” is the rim diameter, already measured in inches. This mixed metric-imperial format is the global standard used by tire manufacturers in the US, UK, Canada, and worldwide. Drivers convert it to inches when comparing tires, checking wheel-well clearance, fitting lift kits, or matching tire sizes across different brands and labeling systems.
How to Convert 315/70R17 to Inches
Tire size conversion uses three steps, combining metric-to-imperial math with the aspect ratio formula:
- Convert section width: 315mm ÷ 25.4 = 12.40 inches (this is tire width)
- Find sidewall height: 315mm × 0.70 (the “70” aspect ratio) = 220.5mm sidewall
- Convert sidewall to inches: 220.5mm ÷ 25.4 = 8.68 inches
- Calculate overall diameter: (8.68 × 2 sidewalls) + 17in rim = 34.36 inches
You can also reverse it: multiply inches by 25.4 to get back to millimeters. For example, 12.40in × 25.4 = 315mm. Most tire shops round the final diameter to 34.4 inches for simplicity, but 34.36 inches is the precise mathematical result.
Real-World Examples: What Does 315/70R17 Look Like?
- Height comparison: A 34.36-inch tire is almost as tall as a standard kitchen countertop (36 inches), making it one of the larger tires found on trucks and SUVs.
- Width comparison: At 12.40 inches wide, the tire’s tread is roughly as wide as a standard laptop laid flat (13–14 inches), giving it a wide, aggressive footprint.
- Shopping context: This size is commonly labeled as a “34-inch tire” or “285/75R17 equivalent” in off-road and truck tire catalogs.
- DIY context: A 34.36-inch tire needs about 2–3 inches of extra fender clearance compared to a stock 32-inch tire, which is why many trucks need a leveling kit.
- Science/math context: The circumference of this tire is about 108 inches (9 feet), meaning it rotates roughly 587 times per mile.
Practical Use Cases
DIY & Home Improvement
If you’re building a truck lift kit or fabricating fender flares, knowing that 315/70R17 equals 34.36 inches tall and 12.40 inches wide tells you exactly how much clearance to cut or add. Most DIY builders round up to 34.5 inches when measuring wheel wells to leave safety margin for suspension flex and steering turn radius.
Fashion & Shopping / Buyer Comparisons
When shopping for tires online, US retailers often list sizes in inches while manufacturers stamp them in metric (315/70R17). Knowing the conversion — 34.36″ x 12.40″ — lets you compare this tire directly against inch-labeled sizes like “34×12.50R17” without guessing.
School, Science & Math
Students studying unit conversion or geometry can use 315/70R17 as a real example: converting millimeters to inches (315 ÷ 25.4), then applying percentage math (aspect ratio) to find sidewall height, and finally using circle geometry (circumference = π × diameter) to find the 108-inch rolling circumference.
Nearby Conversions Table
| Tire Size | Diameter (inches) | Fraction | Diameter (feet) |
|---|---|---|---|
| 275/70R17 | 32.16 in | 32 5/32 in | 2.68 ft |
| 285/70R17 | 32.71 in | 32 23/32 in | 2.73 ft |
| 295/70R17 | 33.26 in | 33 1/4 in | 2.77 ft |
| 305/65R17 | 32.61 in | 32 5/8 in | 2.72 ft |
| 305/70R17 | 33.81 in | 33 13/16 in | 2.82 ft |
| 315/70R17 | 34.36 in | 34 3/8 in | 2.86 ft |
| 285/75R17 | 33.83 in | 33 13/16 in | 2.82 ft |
| 295/75R17 | 34.42 in | 34 7/16 in | 2.87 ft |
| 325/70R17 | 34.91 in | 34 15/16 in | 2.91 ft |
| 315/75R17 | 35.60 in | 35 5/8 in | 2.97 ft |
| 315/70R18 | 35.36 in | 35 3/8 in | 2.95 ft |
Frequently Asked Questions
Q: How many inches is a 315/70R17 tire? A: A 315/70R17 tire is 34.36 inches in overall diameter (height) and 12.40 inches wide. Most tire shops simply round this to a “34-inch tire” or “34.5-inch tire.”
Q: What is 315/70R17 as a fraction in inches? A: The overall diameter of 34.36 inches rounds to 34 3/8 inches as a fraction. The section width of 12.40 inches rounds to 12 3/8 inches.
Q: How many feet tall is a 315/70R17 tire? A: A 315/70R17 tire stands 2.86 feet tall (34.36 inches ÷ 12 = 2.86 ft), just under 3 feet.
Q: How do I convert 315/70R17 back to millimeters? A: The section width is already in millimeters — 315mm. To convert the 12.40-inch width back, multiply by 25.4: 12.40 × 25.4 = 315mm, confirming the original spec.
Q: Is a 315/70R17 taller than a 33-inch tire? A: Yes. A 315/70R17 measures 34.36 inches, which is about 1.36 inches taller than a standard 33-inch tire, giving noticeably more ground clearance.
Q: What common object is about 34.36 inches long? A: A 34.36-inch measurement is close to the height of a standard kitchen counter (36 inches) or slightly taller than a golf club shaft (around 34–35 inches for irons).
Tips for Converting 315/70R17 to Inches
- Mental math shortcut: Divide the millimeter width by 25 (instead of 25.4) for a quick estimate — 315 ÷ 25 = 12.6, close enough to the real 12.40 inches.
- Use decimals for precision, fractions for shopping: Mechanics and spec sheets use decimals (34.36 in), but tire shops and casual buyers use fractions (34 3/8 in) since they’re easier to visualize.
- Common mistake: Don’t forget the aspect ratio applies to the width, not the rim. The “70” means 70% of 315mm, not 70% of 17 inches.
- Double the sidewall: Always multiply sidewall height by 2 before adding the rim diameter — beginners often forget the tire has a sidewall on both the top and bottom.
- Tool tip: Use an online tire size calculator to instantly cross-check your math and compare against other tire sizes side by side.
Conclusion
To sum up, 315/70R17 converts to 34.36 inches in overall diameter and 12.40 inches in section width, making it a popular size for trucks and SUVs needing extra ground clearance. Bookmark this page for quick reference next time you’re comparing tire sizes or planning a lift kit fitment.
Also read WBU Meaning in Text — What Does WBU Mean & How to Use It?
