Tire Size in Inches: Conversion Chart for Every Common Size
Table of contents
- How to convert any tire size to inches
- Tire width in inches: chart from 205 to 335
- What is a 265, 275, 285, 295, 305 or 315 tire in inches?
- 265 tire in inches
- 275 tire in inches
- 285 tire in inches
- 295 tire in inches
- 305 tire in inches
- 315 tire in inches
- Common tire sizes in inches
- Why a real tire can measure differently
- Sizes that are already in inches
- The verdict
Tire sizes in the United States are printed in millimeters, but most of us think about tires in inches. "Will a 285 fit?" "Is that a 33 inch tire?" "How much taller is a 275/70R18 than what I have now?" Every one of those questions comes down to the same simple conversion. Here is how to turn any tire size into inches, with a chart of the most common widths and full sizes already worked out.
Quick answer
To convert tire width to inches, divide the first number by 25.4. A 265 tire is about 10.4 inches wide, a 275 is 10.8, a 285 is 11.2, a 295 is 11.6, a 305 is 12.0 and a 315 is 12.4. For overall height, add twice the sidewall height to the wheel diameter.
How to convert any tire size to inches
Take 275/65R17 as the example. The three numbers you need are the width (275), the aspect ratio (65) and the wheel diameter (17). Only the last one is already in inches.
- Width in inches: divide the width by 25.4. 275 divided by 25.4 is 10.8 inches.
- Sidewall height in inches: multiply the width by the aspect ratio, divide by 100, then divide by 25.4. 275 multiplied by 0.65 is 178.75 mm, which is 7.0 inches.
- Overall diameter in inches: add the sidewall twice, once above the wheel and once below, to the wheel size. 17 plus 7.0 plus 7.0 is 31.1 inches.
So a 275/65R17 is roughly 10.8 inches wide and 31.1 inches tall. The middle number is a percentage, not a measurement, which is why the same aspect ratio gives different sidewall heights on different widths. Our guide to tire aspect ratio explains that part in more detail.
Tire width in inches: chart from 205 to 335
This is the number most people are after when they ask what a 285 or a 305 tire is in inches. It is the section width, measured across the widest point of the sidewalls when the tire is mounted and inflated.
| Tire width (mm) | Width (inches) | Tire width (mm) | Width (inches) |
|---|---|---|---|
| 205 | 8.1 | 275 | 10.8 |
| 215 | 8.5 | 285 | 11.2 |
| 225 | 8.9 | 295 | 11.6 |
| 235 | 9.3 | 305 | 12.0 |
| 245 | 9.6 | 315 | 12.4 |
| 255 | 10.0 | 325 | 12.8 |
| 265 | 10.4 | 335 | 13.2 |
Each step of 10 mm adds a little under 0.4 of an inch. Going from a 265 to a 285 makes the tire about 0.8 inches wider, which is why a wider tire is not automatically a safe swap: it has to clear your suspension, fenders and frame at full steering lock.
What is a 265, 275, 285, 295, 305 or 315 tire in inches?
265 tire in inches
A 265 tire is about 10.4 inches wide. Common sizes such as 265/70R17 stand about 31.6 inches tall, and 265/65R17 about 30.6 inches.
275 tire in inches
A 275 tire is about 10.8 inches wide. A 275/65R17 is about 31.1 inches tall, a 275/65R18 about 32.1 inches, and a 275/60R20 about 33.0 inches.
285 tire in inches
A 285 tire is about 11.2 inches wide. A 285/75R16 is about 32.8 inches tall and a 285/70R17 about 32.7 inches, which is why both are often described as roughly 33 inch tires.
295 tire in inches
A 295 tire is about 11.6 inches wide. The height depends entirely on the aspect ratio and wheel, so use the three-step method above for your exact size.
305 tire in inches
A 305 tire is about 12.0 inches wide. A 305/55R20 stands about 33.2 inches tall, while a low-profile 305/30R26 reaches about the same height on a much larger wheel with a sidewall of only 3.6 inches.
315 tire in inches
A 315 tire is about 12.4 inches wide. A 315/70R17 is about 34.4 inches tall, one of the larger sizes that still fits a 17 inch wheel.
Common tire sizes in inches
The full conversion for sizes people search for most often. Select a size to see its specs and the tires we have in it.
| Tire size | Width (in) | Sidewall (in) | Overall diameter (in) |
|---|---|---|---|
| 225/65R17 | 8.9 | 5.8 | 28.5 |
| 235/65R17 | 9.3 | 6.0 | 29.0 |
| 245/75R16 | 9.6 | 7.2 | 30.5 |
| 265/65R17 | 10.4 | 6.8 | 30.6 |
| 265/70R17 | 10.4 | 7.3 | 31.6 |
| 265/75R16 | 10.4 | 7.8 | 31.6 |
| 265/70R18 | 10.4 | 7.3 | 32.6 |
| 275/65R17 | 10.8 | 7.0 | 31.1 |
| 275/55R20 | 10.8 | 6.0 | 31.9 |
| 275/65R18 | 10.8 | 7.0 | 32.1 |
| 275/60R20 | 10.8 | 6.5 | 33.0 |
| 275/70R18 | 10.8 | 7.6 | 33.2 |
| 275/65R20 | 10.8 | 7.0 | 34.1 |
| 285/60R18 | 11.2 | 6.7 | 31.5 |
| 285/70R17 | 11.2 | 7.9 | 32.7 |
| 285/75R16 | 11.2 | 8.4 | 32.8 |
| 305/45R22 | 12.0 | 5.4 | 32.8 |
| 305/30R26 | 12.0 | 3.6 | 33.2 |
| 305/55R20 | 12.0 | 6.6 | 33.2 |
| 305/45R24 | 12.0 | 5.4 | 34.8 |
| 315/70R17 | 12.4 | 8.7 | 34.4 |
Not in the chart? Search your exact size and you will see its specs and the tires available in it:
Find tires in your size
It's on your tire's sidewall or the driver-side door placard — e.g. 205/55R16
Why a real tire can measure differently
The numbers above are the design dimensions, and they are what you should use to compare sizes. A tire on your vehicle can measure a little differently for four ordinary reasons.
- Rim width. The section width is defined on a specific measuring rim. A wider or narrower wheel pulls the sidewalls out or in slightly.
- Load and inflation. A loaded tire squats, so the distance from the wheel center to the ground is shorter than half the overall diameter.
- Tread wear. A worn tire is shorter than a new one, which matters when you mix new and used tires on the same axle.
- Manufacturer and model. Two tires with the same size printed on them can differ by a fraction of an inch, especially aggressive all-terrain and mud-terrain treads.
When you change sizes, the rule of thumb is to keep the new overall diameter within about 3 percent of the original. Beyond that, your speedometer, odometer and wheel-speed systems start reading noticeably wrong.
Key takeaways
- Divide the tire width by 25.4 to get inches: 265 is 10.4, 275 is 10.8, 285 is 11.2, 295 is 11.6, 305 is 12.0, 315 is 12.4.
- Sidewall height is the width times the aspect ratio, divided by 100, then by 25.4.
- Overall diameter is the wheel size plus twice the sidewall height.
- A 275/65R17 is about 10.8 inches wide and 31.1 inches tall.
- Real tires vary slightly with rim width, load, wear and brand.
- Keep a replacement size within about 3 percent of the original overall diameter.
Sizes that are already in inches
Some off-road and light truck tires skip the metric format entirely. A size like 33x12.50R20 already reads in inches: about 33 inches tall, 12.5 inches wide, on a 20 inch wheel. These flotation sizes have no aspect ratio to convert, and they are compared to metric sizes by overall diameter. Our guide to what size a 33 inch tire is lists the metric sizes that match the common 33s and 35s. The full breakdown of the rest of a sidewall, including the load index and speed rating, is in our guide to what tire numbers mean.
The verdict
Converting a tire size to inches takes three small sums: divide the width by 25.4, work out the sidewall from the aspect ratio, and add it twice to the wheel size. Use the charts above for the common sizes, use the method for anything else, and compare sizes by overall diameter rather than by width alone. Before you change size, check the load index and speed rating against your door placard as well, because a tire that fits is not automatically a tire that is rated for your vehicle.
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Disclaimer: This content is for general informational purposes only and is not a substitute for professional automotive advice. Always confirm tire size, load rating, and inflation pressure against your vehicle's door placard and owner's manual, and consult a qualified tire professional before making changes to your vehicle's tires.
