What is my hub bore size?
Your hub bore size is the inner diameter of the wheel hub opening that the wheel sits on. It must match your vehicle’s hub for proper centering and safe operation. The exact size varies by model and wheel, so check official specs or measure carefully to be sure.
What hub bore size means and why it matters
The hub bore, also called the center bore, is the hole in the middle of the wheel that fits over the vehicle’s hub. When the bore matches the hub, the wheel is centered correctly, reducing vibrations and uneven wear. If the bore is larger, hub-centric rings may be used to center the wheel; if it’s smaller, the wheel won’t fit without modification. Getting the size right is essential for safety and performance.
How to determine your hub bore size
To identify your hub bore size, use one or more of these methods. Each approach helps verify the correct diameter so you can select wheels that fit properly.
- Check the vehicle’s official specifications, which are listed in the owner’s manual, service manuals, or manufacturer websites. Look for wheel or hub bore measurements specific to your model.
- Lookup the VIN (Vehicle Identification Number) with a dealership or manufacturer portal. Build sheets or specs often include hub bore details for your exact configuration.
- Measure the wheel’s center bore directly with a digital caliper. Record the diameter to the nearest 0.01 mm (or 0.1 mm) and repeat at multiple points around the bore to confirm circularity.
- Consult the wheel manufacturer or retailer for the exact center bore of your wheel model. Compare that value to your vehicle’s hub size to determine fit.
- Ask a professional shop or technician. If you’re unsure, a quick measurement and cross-check from a qualified source can prevent costly mistakes.
Using these methods will help you determine the hub bore size accurately and avoid misfits that can cause vibration or mounting issues.
When and how hub-centric rings come into play
If you discover that the wheel center bore is larger than the hub diameter, hub-centric rings can center the wheel and improve fit. If the bore is smaller than the hub, the wheel is not suitable without modification, which is generally not recommended.
- Choose a hub-centric ring with an inner diameter equal to the hub bore and an outer diameter matching the wheel’s center bore.
- Ensure the ring thickness is appropriate for the gap between hub and wheel; rings are available in various thicknesses to suit different gaps.
- Only purchase rings from reputable manufacturers and ensure compatibility with your wheel and hub spec.
Properly selected hub-centric rings can improve centering and reduce vibrations, but they are optional and only necessary when there is a mismatch between hub and wheel bores.
Practical tips and safety considerations
Here are key takeaways to keep you safe and informed when dealing with hub bore size:
- Always confirm that the wheel bore is at least as large as the hub bore. If the bore is smaller, the wheel will not fit safely.
- Prefer wheels whose center bore matches the vehicle’s hub bore to minimize the need for rings and potential runout issues.
- When using rings, ensure correct inner and outer diameters and thickness to avoid improper seating or vibrations.
- Consult a professional if you’re unsure about fitment, especially for critical applications like performance or off-road wheels.
Accurate hub bore sizing is a foundational step in wheel replacement. Taking the time to verify size prevents misalignment, vibration, and safety risks on the road.
Summary
Hub bore size is the wheel’s center hole diameter that must align with your vehicle’s hub for proper centering and safety. Determine it by checking official specs, using your VIN, or precisely measuring the wheel’s center bore with a caliper. If there’s a mismatch, hub-centric rings can help, but the best practice is to choose wheels whose center bore matches the hub bore. Always verify fitment before driving to ensure a smooth, safe ride.
How do I know my bore size?
Steps
- Check the clearance specifications for the engine you're working with.
- Set a micrometer to the estimated diameter of your engine's cylinders.
- Clamp the micrometer into a vice lightly.
- Fit a dial bore gauge with a head that matches the size of the cylinder.
- Zero your dial bore gauge to the micrometer.
Where can I find the wheel bore size?
The center bore measurement of a wheel is the size of the hole on the backside of the wheel, usually measured in millimeters (mm). In some countries, this is also referred to as spigot size. When shopping for wheels or hub centric rings, it's important to know the center bore of the wheels.
Does hub bore size have to be exact?
No, the hub bore size does not have to be an exact match, but the wheel's center bore must be equal to or larger than the vehicle's hub size. A wheel with a larger center bore can be safely mounted using a hub-centric ring to fill the gap and ensure proper alignment and safety. It is unsafe to use a wheel with a center bore smaller than the vehicle's hub, as the wheel will not seat properly.
Why an exact match is ideal
- Proper centering: An exact match ensures the wheel is perfectly centered on the hub, which is the most secure and stable way to mount a wheel.
- Prevents vibrations: Without a snug fit, vibrations can occur, especially at higher speeds, which can affect steering and overall vehicle stability.
- Reduces wear: An incorrect fit can lead to uneven load distribution, causing premature wear on steering components and tires.
When the sizes don't match
- Wheel bore larger than hub: This is a common situation with aftermarket wheels, which often have a universal, larger bore to fit multiple vehicles.
- Solution: Use a hub-centric ring to adapt the wheel's larger bore to the vehicle's smaller hub. This ensures the wheel is properly centered and safe to drive.
- Wheel bore smaller than hub: This is an unsafe condition because the wheel cannot sit flush against the hub.
- Reason: The wheel will be centered only by the lug nuts, which can cause uneven stress and lead to vibrations or even a wheel failure.
How do I know my hub bore size?
To measure hub bore, clean the wheel's center and measure the diameter of the central hole using either a caliper or a tape measure. For the most accurate reading, use a digital or dial caliper, but a tape measure is a suitable alternative. Place the caliper's inside probes across the widest part of the hole, or lay the tape measure across the center, to get the diameter measurement in millimeters (mm).
This video demonstrates how to measure the center bore of a car wheel: 59sCar LuvversYouTube · Feb 3, 2024
Steps to measure hub bore
- Prepare the wheel:
- Remove the wheel from the vehicle.
- Clean the center hub area to remove any dirt or debris.
- Remove any center cap if it covers the hole.
- Gather your tools:
- A caliper (digital or dial) is the most accurate tool.
- A tape measure or ruler can be used if a caliper isn't available.
- A telescoping bore gauge is also a highly accurate option.
- Take the measurement:
- With a caliper: Use the inside diameter (ID) measurement tool on the caliper. Place the probes inside the bore and carefully expand them until they touch the sides, then lock them and read the measurement.
- With a tape measure or ruler: Place the end of the tape measure at one edge of the bore. Extend the tape across the center of the hole to the opposite edge. You can also use a stick or wire to get a snug fit inside the bore, remove it, and then measure the stick.
- With a telescoping bore gauge: Insert the gauge into the bore, expand it until it is snug, and then withdraw it to measure the gauge with calipers or a ruler.
- Record the measurement:
- Write down the diameter, typically in millimeters (mm).
- Double-check the measurement a couple of times to ensure accuracy.
- Use a reference:
- For new wheels, the center bore size is usually listed in the product details.
- For aftermarket wheels, you may need hub-centric rings to fit them to the vehicle's hub correctly. The rings will have an inner diameter that matches the vehicle's hub and an outer diameter that matches the wheel's center bore, as shown in this YouTube video.
This video explains what center bore is and how it relates to hub rings: 55sauto123YouTube · May 25, 2011
