How to Measure Push Through Center Caps: Bore, Height & End Style
How to measure push through center caps correctly starts with the wheel’s center opening, but diameter alone is not enough. You also need to check the cap’s barrel diameter, barrel height, total height, inner clearance, and end style. These measurements help you avoid buying a cap that looks right but does not fit.
If you are replacing a missing or damaged cap, the good news is that you do not need special shop equipment. A digital caliper, a few minutes, and the right measurements are usually enough to narrow down the correct push-through center cap.
What Measurements Do You Need for a Push-Through Center Cap?
Push-through caps are installed from the back of the wheel, so the part that enters the wheel matters more than the cap’s front appearance.
Here are the main measurements to record:
| Measurement | What it tells you |
| Bore / barrel diameter | The diameter of the section that fits into the wheel |
| Maximum diameter | The widest part of the cap |
| Barrel height | How far the barrel extends through the wheel |
| Total height | Overall depth of the cap |
| Inner diameter | Available space inside the barrel |
| Hub clearance | Whether the cap has room around the hub |
| End style | How the back/end of the cap is designed |
This matters because a push-through cap listed as 3.31 inches, for example, does not necessarily measure 3.31 inches across its entire outside face. Product specifications can list separate barrel, overall, and height measurements.
If you want to understand the basic design first, read our guide to what push-through center caps are and how they fit. It covers their purpose, common sizes, and general fitment.
Tools You Need to Measure Push-Through Center Caps
You only need a few basic tools:
- Digital caliper — best for accurate measurements
- Ruler — useful if a caliper is not available
- Tape measure — helpful for larger dimensions
- Pen and paper or your phone — record every measurement
- Clean cloth — remove dirt around the bore
A digital caliper is the best option because center-cap fitment can depend on small differences in size. Engineer Fix also recommends using digital calipers when measuring a removed center cap.
Tip: Measure in millimeters when possible. It makes it easier to compare your measurements with product specifications.
How to Measure Push Through Center Caps Step by Step
1. Remove the Old Center Cap
If you still have the original cap, remove it carefully.
A push-through cap normally comes out from the back of the wheel. Do not pry against the visible face if doing so could damage the cap or wheel.
Once removed, inspect the back.
Look for:
- Part numbers
- Brand markings
- Size markings
- Barrel shape
- Retaining features
- Any markings molded into the plastic or metal
The old cap is often your best reference.
If you do not have the original cap, you can measure the wheel’s center opening instead. An expert answer from etrailer also recommends measuring the wheel’s pilot diameter when selecting a replacement center cap.
2. Clean the Center Opening
Before measuring, clean dirt and buildup from the wheel’s center bore.
This small step matters because rust, dirt, old grease, or debris can change the reading.
You want to measure the actual metal opening, not the dirt sitting inside it.
3. Measure the Bore or Barrel Diameter
This is one of the most important measurements.
The barrel is the cylindrical section of the push-through cap that goes into the wheel. Measure the barrel’s outside diameter with your caliper.
If you are measuring the wheel instead of the cap, measure the center bore/pilot opening where the barrel sits.
Why does this matter?
If the barrel is too large, the cap will not go in.
If it is too small, the cap may not hold securely.
This is why buying a push-through center cap simply because the front looks similar is risky.
For example, American Wheels lists push-through products with separate measurements for barrel diameter, maximum diameter, barrel height, and total height.
4. Measure the Barrel Height
After measuring the barrel diameter, check its height. The barrel height tells you how far the cylindrical section extends through the wheel. This matters because the cap needs enough barrel length to sit correctly in the wheel.
A barrel that is too short might not seat properly. A barrel that is too long could create clearance problems behind the wheel.
This is especially important on truck, trailer, RV, and specialty wheels where the hub area can differ from one application to another.
5. Measure the Total Height
Next, measure the complete height or depth of the cap. Place the cap on a flat surface and measure from the appropriate mounting point to the deepest point. Do not confuse total height with barrel height.
They are not always the same. For example, a product can have a shorter barrel section but a taller overall cap because the front portion extends farther outward.
American Wheels’ general center-cap measurement guidance also separates outside diameter, inside diameter, and depth because each dimension affects fitment.
6. Check the Inner Diameter
Turn the cap over and inspect the inside of the barrel. Measure the inner diameter where applicable.
This tells you how much room is available inside the barrel and can help confirm whether the cap will clear the hub or related hardware.
For a replacement, do not assume that two caps with the same outside barrel diameter have the same internal dimensions. The outside measurement may match while the internal design is different.
7. Check Hub Clearance
This step is easy to overlook. The cap needs enough room around the hub, axle, bearing area, or other hardware behind the wheel.
A cap can have the correct bore diameter and still be the wrong choice if its depth or internal clearance does not work with the wheel.
This is one reason height and depth measurements matter just as much as diameter. If your wheel has an extended hub or unusual hardware, take extra care before ordering.
8. Check the End Style
The back or end of a push-through center cap can have different designs depending on the application.
Before buying, look at the existing cap and ask:
- Is the back fully closed?
- Does it have a removable plug or top?
- Is there extra clearance around the hub?
- Does the cap cover the hub completely?
- Does the back design match the wheel’s application?
Some trailer-style caps, for example, are designed with removable sections that provide access without removing the entire cap.
Do not ignore the end style just because the diameter matches. The back of the cap needs to work with the space behind your wheel.
How to Measure the Wheel If You Don’t Have the Old Cap
Missing the old center cap does not mean you have to guess. Start by identifying the wheel’s center opening.
Step 1: Remove the wheel if needed
Getting clear access to the center bore makes measurement easier.
Step 2: Clean the opening
Remove dirt or buildup that could affect the reading.
Step 3: Measure the pilot or center bore
Use a digital caliper and measure across the opening.
Step 4: Check the depth behind the wheel
Look at the available space around the hub.
Step 5: Identify the wheel
Record:
- Wheel brand
- Wheel model
- Wheel size
- Vehicle
- Any markings on the wheel
Then compare those details with the cap manufacturer’s fitment information.
Do not rely on the vehicle model alone.
Aftermarket wheels can use completely different center caps from the vehicle’s original wheels. American Wheels also recommends starting with the wheel and its measurements rather than assuming vehicle information is enough.
How to Convert Push-Through Center Cap Sizes
You may see measurements listed in both inches and millimeters.
The basic conversion is:
1 inch = 25.4 mm
Some common examples are:
| Inches | Approx. millimeters |
| 3.19″ | 81.0 mm |
| 3.25″ | 82.6 mm |
| 3.27″ | 83.1 mm |
| 3.31″ | 84.1 mm |
| 4.25″ | 108.0 mm |
| 5.15″ | 130.8 mm |
These conversions are useful when comparing push-through center cap sizes, but do not round your own measurement just to make it match a product listing.
Measure accurately first, then compare the result with the manufacturer’s specifications.
Example: How to Read a Push-Through Center Cap Size
Let’s say a product listing gives several measurements like:
- Barrel diameter: 84 mm
- Maximum diameter: 92 mm
- Barrel height: 72.8 mm
- Total height: 76 mm
- Barrel inner diameter: 82.5 mm
These numbers do not describe five different versions of the cap.
They describe different parts of the same cap.
In simple terms:
- 84 mm tells you about the barrel that fits the wheel.
- 92 mm is the widest outside measurement.
- 72.8 mm describes the barrel height.
- 76 mm describes the overall height.
- 82.5 mm tells you about the inside of the barrel.
American Wheels product specifications use this type of detailed measurement, which is a good example of why looking at the full specification is better than shopping by one size number.
Common Push-Through Center Cap Measuring Mistakes
Measuring the wheel diameter
A 20-inch wheel does not need a 20-inch center cap. The center cap fits the much smaller center opening.
Measuring only the front of the cap
The front may look perfect while the barrel is the wrong size.
Ignoring height
A correct diameter does not guarantee correct depth.
Buying by vehicle make alone
A Ford, Chevy, Ram, or other vehicle can have different wheels with different center-cap requirements.
Assuming all push-through caps are universal
They are not. Push-through center caps come in many sizes and designs, so fitment needs to be confirmed before ordering.
Rounding your measurement too much
If your caliper shows a measurement that is slightly different from what you expected, do not simply round it to the nearest size. Measure again.
Choosing a cap because it “looks close”
This is one of the most common buying mistakes. Fitment beats appearance.
What If Your Measurement Falls Between Two Sizes?
Do not force the closest-looking size.
If your measurement seems to fall between two product sizes:
- Clean the bore again.
- Measure it in more than one spot.
- Check your caliper.
- Measure the old cap if you still have it.
- Check the wheel brand and model.
- Compare all listed dimensions, not just the main size.
A cap that is too small can be loose, while one that is too large may not install correctly.
If you are unsure whether your wheel uses a push-through or snap-in design, our guide to push-through vs. snap-on center caps explains how the two mounting styles differ.
How to Match Your Measurements to the Right Center Cap
Once you have your numbers, use this order:
1. Confirm the mounting style
Make sure the wheel actually uses a push-through cap.
2. Match the bore/barrel diameter
This is one of the most important fitment measurements.
3. Confirm the barrel height
Make sure the cap reaches the correct depth.
4. Check total height
Make sure there is enough space around the hub.
5. Check inner clearance
Make sure the cap does not interfere with hardware behind the wheel.
6. Check the end style
Make sure the back of the cap suits your wheel and application.
7. Compare the complete product specifications
Do not buy based on one number.
Quick Push-Through Center Cap Measurement Checklist
Before placing your order, make sure you have:
- ✓ Center bore measurement
- ✓ Barrel diameter
- ✓ Maximum outside diameter
- ✓ Barrel height
- ✓ Total height
- ✓ Inner diameter
- ✓ Hub clearance
- ✓ End style
- ✓ Wheel brand and model
- ✓ Original cap part number, if available
If you have all of these, you are in a much better position to find the correct replacement.
Final Thoughts
Measuring push-through center caps is not difficult, but measuring only one dimension can lead to the wrong replacement.
Start with the bore or barrel diameter, then check the barrel height, total height, inner diameter, hub clearance, and end style. If you still have the original cap, use it as your main reference. If it is missing, measure the wheel’s center opening and identify the wheel as accurately as possible.
At American Wheels Company, fitment details matter because a center cap needs to do more than look right—it needs to fit the wheel correctly. Once you have your measurements, compare them with the specifications of the replacement cap before ordering.
FAQs: How to Measure Push Through Center Caps
What size push-through center cap do I need?
You need a cap that matches your wheel’s center bore and has the correct barrel diameter, height, and clearance. The wheel brand and model can also help confirm fitment.
How do I measure push-through center caps?
Remove the old cap if possible, then measure the barrel diameter, maximum diameter, barrel height, total height, and inner clearance with a digital caliper. If the old cap is missing, measure the wheel’s center bore.
Is center bore the same as center cap diameter?
Not always. The wheel’s center bore is the opening in the wheel, while a center cap can have several different diameter measurements. The barrel diameter is usually the measurement most closely related to the opening it fits into.
What is barrel diameter on a center cap?
Barrel diameter is the width of the cylindrical section that enters the wheel. It is a key measurement for push-through center cap fitment.
How do I measure center cap height?
Measure the cap from its mounting point to the deepest or highest point, depending on the specification being requested. Also check barrel height because total height and barrel height can be different.
Can I measure the wheel if I don’t have the old cap?
Yes. Measure the wheel’s center bore or pilot opening with a digital caliper. Also check the available space behind the wheel. Measuring an existing cap is usually easier, but the wheel can be measured when the original is gone.
Are push-through center caps universal?
No. Push-through caps come in different bore sizes, heights, and designs. Always confirm the complete dimensions and mounting style before ordering.
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