How To Measure Your Car Wheel Rim Sizes (Ultimate Guide)

Car wheels are often taken at face value, usually overlooked for the more aesthetically pleasing aspects of the vehicle. However, if you need a tire changed, it is important to know the dimensions of the wheel rim, leaving many to wonder how they go about measuring their car’s wheel rim sizes.

There are 4 things to consider when measuring car wheel rim sizes. These are the width and diameter, measured in inches not including the rim lip, and the offset and backspacing, which are measured in millimeters and do include the rim lip. These can be measured using a ruler or tape measure.

Other features such as bolt patterns are also important when getting to know the details of your car’s wheels. In this article we will take a deeper look into bolt patterns, as well as the other aforementioned features, to give you a better understanding of the importance of your wheel rim sizes.

Why Is It Important To Measure Your Car’s Wheel Rims?

There are a few reasons why it is important that you check your wheel rims. Measuring a rim correctly and accurately will ensure that you know the correct size tire that you need in case you require a replacement. As well as being dangerous, driving with tires that are either too big or too small can put your car at great risk of being damaged.

Using The Right Size

If your tires are too small for the wheel rim, you will be at risk of the car sending incorrect information to the speedometer, the check engine light being triggered, and even faults to the vehicle’s anti-lock brake system (ABS). They can also lower the suspension of your car beyond its normal limit, meaning you’ll be painfully scraping over every speed bump.

Using tires that are too big for the wheel rim will also be dangerous, as they could end up becoming too loose and dislodging from the metal wheel frame. In short, it is important that you have a general knowledge of the size of your wheel rims to make sure you don’t get caught out in the event of a tire replacement.

Fitting The Wheel On

As well as the overall size of the wheel rim, it is important to know about other details, such as the wheel’s offset and backspacing, and its bolt pattern. The offset and backspacing will determine how your wheel looks when it is fitted on, and whether it will be protruding or too close to the car’s chassis. The bolt pattern is very important as you can’t change it.

Your vehicle will have a certain number of bolt holes, also known as lug holes, which the wheel can be fitted on to. You cannot use a set of aftermarket wheels that have a different bolt pattern to the stock wheels originally fitted to your car without extra modifications. Therefore, it is important to know the less obvious details about your wheel rims, to save you from wasting any time or money.

Understanding Car Wheel Bolt Patterns

Bolt patterns refer to the specific pattern of holes, known as lug holes, on the wheel, used to lock the wheel onto the car. These holes are where the lug nut and lug bolt fix on and are arranged in a circle around the center of the wheel. The most common patterns feature four, five or six lug holes, with three or eight also available. Most modern vehicles will have five lug holes.

The importance of bolt patterns cannot be understated, as you will need to match up the wheel’s pattern to the car in order to secure the wheel on properly. This is something that can’t be modified, and if you are buying a set of aftermarket wheels, you will need to make sure they match the same bolt pattern as the original stock wheels. 

You will also need to consider the diameter of the lug holes in order to get the right lug nuts and bolts to securely fasten the wheel onto the car. These diameters are measured in millimeters and will appear next to the number of holes the wheel has. For example, if a wheel has a four-bolt pattern and holes with a 100-millimeter diameter, the pattern will be listed as 4×100. 

Four & Five-Lug Bolt Patterns

Four and five lug bolt patterns are the most common on the market and are usually fitted on small to medium sized cars. As they are the most common bolt patterns, they will be the easiest to find on the market. The most common four-lug bolt patterns are:

  • 4×98
  • 4×100
  • 4×108
  • 4×110
  • 4×114.3

There is a lot more choice for five-lug bolt patterns with more than 15 combinations commonly available.

Six & Eight-Lug Bolt Patterns

Six-lug bolt patterns are most often found on mid to full-size SUVs, as well as other large vehicles such as trucks. They are also readily available, meaning you will likely have a lot of choice if you are looking at aftermarket wheels. Eight-lug bolt patterns aren’t commonly found on your average road cars and are usually reserved for more luxurious vehicles. 


• It’s important to understand your car’s rim sizes to ensure you use the right size of wheel

• Not doing so can be dangerous and cost you in the long run

• You’ll also need to match the car’s bolt pattern if you’re buying aftermarket wheels

Wheel Offset & Backspacing Explained

Wheel offset and backspacing are two of the most important things to consider when choosing your set of custom wheels. The two terms are often confused as the same thing, and while they are related, they have different attributes that each play a role in how your overall ride feels. 


Offset is the measure of distance from the centerline of the wheel to the mounting surface. Offsets can be either positive, where the wheel’s mounting surface is closer to the outboard side of the wheel, or negative, where the mounting surface is closer to the inboard side of the wheel. 

Negative offsets tend to look more aggressive, but they don’t always work on every vehicle. Positive offsets will usually mean that the wheel has a flatter face. Offset is measured in millimeters.


Backspacing measures the distance between the mounting surface and the inner edge of the wheel. In most cases, the backspacing number will be a positive, and will only be negative on a select few vehicles, such as certain pickup truck models. 

The higher the backspacing measurement, the more the wheel will be pushed towards the car’s centerline. To measure backspacing, you lay the wheel on its face, place a straight edge across it, and measure the distance to the mounting surface. Like when measuring the offset, backspacing is also measured in millimeters.

How To Tell What Size Rims You Have

How To Measure Wheel Rim Width

Measuring width is important as it determines what size tire you need to fit in order to prevent any negative impact on the car’s performance. When it comes to choosing the tire, make sure it is no more than 1.3 cm (0.5 in) smaller or larger than the width of the rim, otherwise it may be deemed too dangerous to use. 

To measure the width of your wheel rim:

  1. Lay the wheel upright as if it were fitted to a car
  2. Place a measuring tape between both rim lips on either side of the wheel

Wheel widths are reported in half-inch increments, so you’ll likely have a number that ends in either 0 or .5. If not, it is important to remeasure, as getting an accurate width measurement is very important. To reiterate, wheel width measurements don’t take the lips of the rim into consideration, just the space in between.

How To Measure Wheel Rim Diameter

To measure the diameter of your wheel rim:

  1. Lay it on its face, on a flat surface
  2. Place the measuring tape, so it is hooked on the outside of the lip of the rim
  3. Stretch the measuring tape so that it bisects the wheel and measures the distance to the lip on the opposite side – This will help you to find the outer diameter of the wheel rim
  4. Measure the distance from the outside of the rim’s lip to the barrel (the flat surface in the center of the rim’s width)
  5. Subtract this measurement twice from the measurement you got at step 3

Here you are essentially measuring the height of the rim’s lip (step 4), before then subtracting it from the lip-to-lip diameter measurement (step 3) to reveal the diameter measurement. Remember, the wheel’s true diameter does not include the size of the wheel’s lip.

Once you have subtracted the rim lip measurement twice (as there’s a lip at the top and the bottom of the rim), you will have the diameter measurement. Both the width and diameter of a wheel are measured in inches, unlike offset and backspacing measurements, which are measured in millimeters.

How To Measure Wheel Rim Offset 

There are three types of offset to consider during measurement: positive offset, negative offset and zero offset. Positive offset is where the mounting hub is towards the front of the wheel away from the center of the car. A negative offset is the opposite to this, where the mounting hub is closer to the car’s center. Zero offset is when the mounting hub is placed in the center of the wheel. 

KEY TIP: Make sure to use a ruler with millimeter measurements on it rather than just inches, to avoid having to make any conversions later on

To measure the offset of your wheel rim:

  1. Lay the wheel flat with its back side facing upwards
  2. Lay a straight edge ruler through the middle of the wheel
  3. Using another ruler, measure the distance from the floor to the bottom of the straight edge ruler
  4. Divide this measurement by two, and you will have your centerline
  5. Next, reposition the second ruler so that it’s against the hub in the middle of the wheel
  6. Subtract the number you get here from your centerline number and you will have your offset measurement

If it is a positive number, then you will have a positive offset, and vice versa. If the number is 0, then you have a zero offset.

This number will be important when it comes to choosing the correct set of aftermarket wheels for your vehicle. It will also define how your wheels look when fitted to the car, as wheels with a negative offset will be more protruding and stick out from the car more than wheels with a positive offset. 

How To Measure Wheel Rim Backspacing

Wheel backspacing is measured from the back side of the wheel.

To measure your wheel rim’s backspacing:

  1. Place a straight edge ruler through the center of the wheel across the top lip of the rim
  2. Place a second ruler vertically and measure the space from the wheel’s mounting face to the bottom of the first straight edge ruler – This distance will be your backspacing measurement

When measuring a wheel’s backspace, there are no calculations to be made, just a direct measurement. As with offset, backspacing is measured in millimeters rather than inches. 

How To Measure Wheel Bolt Patterns

To measure your wheel’s bolt pattern:

  1. Lay the wheel flat, with the bolt holes facing upwards.
  2. Count the bolt holes, which will likely amount to either four, five, six or eight lug holes
  3. Measure the distance in millimeters from the middle of the two opposing holes, with your measuring tape or ruler bisecting the wheel’s middle hole – This distance will form the second part of your measurement

So, if you have a four-lug bolt pattern and the distance you measured was 110 millimeters, your measurement will be 4×110. If you have either a four, six or eight holes the measurement will be made easier as there will be two symmetrical holes.

If you have a five-lug bolt pattern you won’t have the pleasure of having two symmetrical bolts. In this case, measure the distance from the outside edge of the bolt to the middle of a bolt on the opposite side of your wheel’s central hole. If, for example, the distance is 108 mm, then your measurement will be 5×108.

Final Thoughts

Knowing the dimensions of your car’s wheel rims will ensure you get a well-fitting tire that won’t do any long-term damage to your car or put you in danger. Thankfully, measuring the rims is simple, and can be achieved with little effort and just a ruler or tape measure.

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