Tire Sizing Explained: Understanding the 315 Tire Dimensions and Fit

Knowing what size tire a 315 70r17 is ensures you purchase the perfect tire for your vehicle.

315 is the section width of the tire measured in millimeters, meaning it has a section width of 12.4 inches.

The sidewall height percentage of a 315 70r17 tire is 70, and the tire height is 34.362, making it near-equivalent to a 35" model.

We'll cover everything from rim diameter to tire revolutions to the overall diameter of the 315 tire in the sections below.

What Tire Size Is A 315?

The 315 in this tire size is a metric measurement representing only the tire width in millimeters.

It doesn't denote the tire tread, outer diameter, wheel rim, inner sidewall, or other measurements.

Usually, you'll see the "315 70r17" tire, which denotes various metrics, as per the following:

• 315 is the tire width in millimeters
• 70 is the aspect ratio or sidewall height in a percentage
• 17 is the wheel circumference in inches

The 315 70r17 tire has a width of 12.4 inches.

To replace a 315 70r17 tire, you must be within three percent of the overall diameter of the original tire.

Therefore, you can replace this tire with any of the following 14 compatible tire sizes:

• 305/65R18
• 285/70R18
• 305/70R17
• 285/75R17
• 345/60R18
• 295/70R18
• 275/80R17
• 295/75R17
• 325/65R18
• 285/75R18
• 305/70R18
• 325/70R17
• 275/80R18
• 315/70R18

How Tall Is A 315 Tire In Inches?

The height of the 315 70r17 tire is 34.362 inches, calculated using the following formula:

• the tire's width x the sidewall height percentage = millimeters
• millimeters x two sidewalls (i.e., the inner sidewall and the outer sidewall) = millimeters
• millimeters divided by 25.4 = inches
• inches + 17"-wheel diameter = approximate tire height

You can see the formula in action in the next section.

What Size Tire Is A 35?

A 35" tire size is a metric measurement referring to the aspect ratio multiplied by the tire width.

The calculation gives you the sidewall height.

After that, multiply it by two because there are two sidewalls per tire, then divide by the wheel inch and add the wheel size.

In formula form, the 35" tire size looks like this:

• 315 = metric tire width measured in millimeters
• 70 = height percentage (i.e., aspect ratio) of the sidewall
• 315 x .70 = 220.5 mm
• 220.5 x 2 side walls = 441 mm
• 441 mm divided by 25.4 to get inches = 17.36"
• 17.36" + 17"-wheel diameter = 34.36" approximate tire diameter

Understanding the differences between imperial and metric is a good idea when it comes to tire size.

Since there are so many tire sizes on the market, knowing the disparities can be the difference between finding the perfect fit for your vehicle and not.

What Is A 315 70 Tire?

A 315 70r17 tire is equivalent to 34.4x12.4R17 inches.

It has a section width of 12.4 inches (i.e., the measurement from the inner sidewall to the outer sidewall) and a rim diameter of 17 inches, representing the wheel size it can be mounted on.

The measurement from the wheel rim to the tire tread, otherwise known as the sidewall height, is 8.7 inches, and it boasts an overall diameter of 34.4 inches, reflecting the outer diameter of the tire.

The outer perimeter or circumference is 108 inches, meaning it performs 587 tire revolutions per mile.

Is A 35-Inch Tire The Same As A 315?

Despite what you may think at first glance, a 315 70r17 tire is the same as a 35-inch tire — 315 dictates the tread width of the tire, and 35" is the tire diameter.

Naturally, the confusion exists due to the difference in reference names.

But it isn't too tricky to understand once you realize there is no difference in the tires themselves; 315/70/17 is simply the metric equivalent size for 35-inch imperial tires.

Conclusion

The 315 70r17 tire has a section width of 12.4 inches, a height of 34.362 inches, and an aspect ratio of 70%.

The overall diameter of the tire is 34.4 inches, so the tire revolves 587 times per mile or 364 times per kilometer.

While you can use certain tire size tools to check the measurements of the 315 70r17 tire, knowing it off the top of your head helps when shopping for that all-important perfect fit.