What metric tire size is 31 inches on a 17 inch rim? The closest matches are 255/70R17 and 275/65R17, both of which calculate to about 31.1 inches tall. If you want something slightly shorter or taller, 235/75R17 comes in around 30.9 inches, while 245/75R17 and 265/70R17 land near 31.5 inches. Which one is right depends on how wide you want the tire and how much room your wheel wells have.
31 Inch Tires on 17 Inch Rims: Metric Size Chart
| Metric Size | Approx. Diameter | Approx. Width |
|---|---|---|
| 235/75R17 | 30.9 in | 9.3 in |
| 255/70R17 | 31.1 in | 10.0 in |
| 275/65R17 | 31.1 in | 10.8 in |
| 245/75R17 | 31.5 in | 9.6 in |
| 265/70R17 | 31.6 in | 10.4 in |
| 285/65R17 | 31.6 in | 11.2 in |
These are calculated figures. Real-world height can differ slightly between brands and tread patterns, so confirm the diameter on the tire maker’s spec sheet before buying.
How the Conversion Works
For a 31-inch tire on a 17-inch wheel, the sidewall needs to add 14 inches of height in total, or 7 inches above and 7 below the rim. Seven inches is about 178 mm. So you’re looking for a size where the width times the aspect ratio lands close to 178 mm. For a 255/70R17, that’s 255 × 0.70 = 178.5 mm, almost exactly right. Doubling that, converting to inches (÷ 25.4), and adding the 17-inch rim gives about 31.1 inches.
The same method works for any size. If you’re comparing larger options, our chart showing what metric size equals a 33-inch tire uses the identical formula.
Choosing the Right Width
Several sizes reach about 31 inches, so width becomes the deciding factor. A narrower tire like 235/75R17 or 255/70R17 is easier to fit, tends to ride quietly, and can cut through snow better. A wider tire like 275/65R17 or 285/65R17 gives a more aggressive look and a bigger footprint, but it’s more likely to rub at full steering lock and needs a wheel wide enough to support it. Check your wheel width and the tire maker’s approved rim width range before you buy.
You may also see flotation sizes such as 31×10.50R15. These list height, width in inches, and rim size directly, but the most common 31×10.50 sizes are made for 15-inch wheels, so on a 17-inch rim you’ll usually be shopping in metric sizes.
After You Install New Tires
Set the pressure to your vehicle’s spec on the door jamb sticker, and if a new tire comes overinflated from the shop, here’s how to let air out of a tire safely. Taller tires can also trigger tire pressure or speedometer quirks, so watch for warnings and see our guide on how to identify a bad tire sensor if one appears. To keep wear even, get an alignment check and follow a regular schedule for rotating your tires, since misalignment can cause tire feathering.
Conclusion
So, what metric tire size is 31 inches on a 17 inch rim? The closest are 255/70R17 and 275/65R17 at about 31.1 inches, with 235/75R17 just under and 245/75R17, 265/70R17, and 285/65R17 just over. Pick based on the width your wheels and wheel wells can handle, then confirm the exact diameter with the tire manufacturer.
Frequently Asked Questions
Is 265/70R17 a 31-inch tire?
It’s close. A 265/70R17 calculates to about 31.6 inches tall, so it’s often grouped with 31-inch tires, though it’s slightly taller than a true 31.
Is 255/70R17 or 265/70R17 closer to 31 inches?
The 255/70R17 is closer, at about 31.1 inches. The 265/70R17 is about half an inch taller and roughly 0.4 inches wider.
Do 31-inch tires need a lift on a stock truck or SUV?
Many midsize trucks and SUVs that come with 17-inch wheels can fit a 31-inch tire stock or with a small leveling kit, but it depends on the vehicle, wheel offset, and tire width.
Will switching to 31-inch tires change my speedometer reading?
If the new tires are taller than stock, yes. The speedometer will read slightly slower than your actual speed, and the difference grows the larger the size change.
