Difference between 35-inch and 315 Tires (Metric vs Standard mm)

When it comes to comparing 35-inch and 315 wide tires, it’s important to understand that these are two different measurements that serve different purposes. The 35-inch measurement is a metric value that represents the width of the tire multiplied by the aspect ratio, which is the height of the sidewall. On the other hand, 315 is the tread width in millimeters, and 35 inches refers to the tire diameter. In most cases, 315/70/17 is considered the accepted metric equivalent size for standard or imperial 35-inch tires.

Breaking Down the Measurements

To better understand the relationship between the metric and standard measurements, let’s break it down into a simple formula:

Tire Size: 315/70R17 (35″)

  • 315: The metric width of the tire measured in millimeters
  • 70: The height percentage (Aspect Ratio) of the sidewall
  • 315 width x 0.70 = 220.5mm
  • Divide mm by 25.4 to get inches
  • 220.5mm x 2 sidewalls = 441mm (divided by 25.4 = 17.36″)
  • 17.36″ + 17″ wheel = 34.36″ approximate tire diameter.

It’s essential to note that tire sizes can vary slightly across different manufacturers due to differences in construction, weight, pattern, load rating, ply ratings, tread depth, etc. To determine the exact diameter of a tire, it is recommended to visit the tire manufacturer’s website and check the specific manufacturing specifications for that tire.

Metric vs Imperial Measurements

Understanding the difference between metric and imperial measurements is crucial when it comes to tire sizes. Metric measurements are expressed in millimeters, while imperial or standard measurements are expressed in inches. Having this knowledge can help you find the perfect fit for your vehicle, considering the wide range of tire sizes available today.

Considerations for Fitting 35-inch Tires

If you are considering fitting 35-inch tires on your vehicle, there are a few factors to take into account:

Lift Kit

Typically, a minimum 4″ lift kit is necessary to accommodate 35-inch tires on a vehicle with an Independent Front Suspension (IFS). Depending on the specific vehicle, additional modifications may be required to prevent tire scrubbing when turning the wheels at full lock. Retaining full functionality and articulation is important for off-road driving.

Wheel Offset

Wheel offset or backspacing is an often overlooked factor that can impact tire fitment. Negative offset wheels can create complications, including excessive wheel “poke.” Backspacing refers to the distance from the hub mounting surface to the inside edge of the wheel, while offset is measured in millimeters and determines how the wheels sit inside the wheel wells. Finding the right balance between keeping the tires within the wheel guards and preventing scrub on arches, UCA, brake calipers, etc., is crucial.

Fender & Arch Trimming

To fit 35-inch tires properly, some plastic liners on the inner fender guards may require trimming to prevent scrubbing during full articulation. It may also be necessary to roll the wheel arches, depending on the vehicle and available space. Ensuring proper fender clearance and backspacing is essential, especially when dealing with wider and taller tires that require more wheel arch clearance while off-roading and turning at full lock. Additionally, bump stops play a vital role in preventing tire rubbing and should not be overlooked.

Speedometer Accuracy

Upgrading from stock tires to larger ones can affect speedometer accuracy. With a taller aspect ratio, the wheel circumference increases, leading to potential discrepancies in speedometer readings. When upgrading to 35-inch tires, the actual speed traveled may be higher than what the speedometer indicates. It’s important to be aware of this difference and adjust accordingly.


Fitting 35-inch tires on your vehicle can provide improved ground clearance and a more aggressive appearance. However, several variables should be considered before making this upgrade. Determine your primary purpose for the upgrade, whether it’s purely aesthetic or if you require maximum off-road capability while maintaining articulation. Researching and understanding the specific requirements for your vehicle and tire combination is crucial to ensure a successful fitment and optimal performance.

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