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How to Measure your Wheels | Wheel Size & Wheel Width

Created by Tyler Rodriquez / 10 min read
Date Created: 8/19/2016
Last Updated: 2/8/2024

One of the most common questions in the automotive industry is "How do I correctly measure my wheel?". This is usually a question asked when someone is planning on upgrading wheels. Although many measurements go into measuring a wheel for optimal fitment, we will touch on the most important ones in this article.

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How to Measure Wheel Sizes

If you are unsure the overall size of your wheels, there are a few things to consider when attempting to measure the dimensions. You will want to find the following:
  • Diameter
  • Width
  • Offset
  • Backspacing
  • Bolt Patterns

How To Measure Wheel Diameter

With the Wheel Diameter, keep in mind that there are two measurements to consider: Overall Wheel Diameter and Actual Wheel Diameter.

When measuring for the Overall diameter, you will want to measure from the outside lip to outside lip of the wheel with a measuring tape (Shown by the Green Line in the photo below).


When measuring for the Actual Diameter, you will want to measure from the inside of the Barrel of the wheel (Shown by the Red Line in the above photo). Example: A wheel with an actual Diameter of 18” will have an overall diameter of around 19.5”.

How To Measure Wheel Width

Measuring the Wheel width or rim width is similar to measuring the Diameter. You will want to measure wheel width from the Barrel Section and not the overall outside width (See Picture Below).



How To Measure Wheel Offset

The offset of a wheel is the distance from the hub mounting surface to the center line of the wheel. This is an important measurement to keep an eye on when choosing your next set of Mustang wheels. The wheel offset is measured in millimeters and results in three different types of offsets.
The Three Types of Offset
  • Positive Offset: The hub mounting surface is toward the face of the wheel.
  • Negative Offset: The hub mounting surface is toward the back of the wheel.
  • Zero Offset: The hub mounting surface is even with the centerline of the wheel.




How To Measure Wheel Backspacing

The backspacing is the distance from where the hub section of the wheel contacts the hub surface of the car to the back lip of the wheel (See picture below). Backspacing is always measured in inches and is closely related to the offset so that means when you change one it immediately affects the other.

This is extremely important because it determines the clearance of the wheel in the wheel well. Also, it affects how much the wheel will stick out past the fender. You can measure a wheel’s backspacing by running a straight edge across the rim bead (without a tire) and dropping another straight edge or Tape measure/ruler down to the wheel face, measuring that distance. (See picture below) You will also need to take into consideration the tire size.
How to Measure your Wheels - How to Measure your Wheels


How To Measure Wheel Bolt Pattern

The bolt pattern consists of two numbers and looks like this: 5×4.50. The first number in this example(5) indicates how many bolt holes or studs are on the vehicle while the other number (4.50) describes the diameter of the circle formed by those 5 holes or studs. They are listed in either inches or millimeter units (4.50 is inches). Another example: a bolt pattern of 4×100 indicates a pattern with 4 lugs on a circle with a diameter of 100mm.



Using these tools, you will be able to find the overall dimensions of the wheels you have! Many wheel manufacturers will also have the Diameter and Width Cast in the back of the wheel (example: 17x9) to make it easy to know the main size.

Source: Discount Tire

FAQs

How Do You Tell The Width Of A Rim?

To measure the width of a rim, you can use a ruler or tape measure to determine the distance between the inner edges of the rim where the tire sits. This measurement represents the rim width, typically expressed in inches or millimeters.

How Do You Know If A Tire Will Fit A Rim?

To determine if a tire will fit a rim, you need to ensure compatibility in terms of both diameter and width. Match the tire's diameter to the rim's diameter (e.g., 15-inch tire for a 15-inch rim) and verify that the tire's width range is suitable for the rim width. Additionally, consider aspects like tire profile and clearance to ensure proper fitment.To measure rim width, use a ruler or caliper to determine the distance between the inner edges of the rim where the tire sits. Rim offset is measured from the mounting surface to the centerline of the rim, either positive (toward the front of the rim) or negative (toward the back). Use a straightedge to measure this distance accurately.

 

How Do You Measure Rim Width and Offset?

To measure rim width, use a ruler or caliper to determine the distance between the inner edges of the rim where the tire sits. Rim offset is measured from the mounting surface to the centerline of the rim, either positive (toward the front of the rim) or negative (toward the back). Use a straightedge to measure this distance accurately.


Thumbnail image of the author of this article, Tyler Rodriquez.

About the Author

Tyler has written content for Late Model Restoration for nearly 8 years, producing over 300 articles. As an avid New Edge fan, Tyler has owned 4 2004 Mustangs and an 88 Convertible Fox Body. Read more...