What size nut is on a axle nut?

There isn't a single universal size—the axle nut size varies by vehicle make, model, and trim. In practice, axle nuts range from about 22 mm to 36 mm across flats, with common sizes including 27 mm, 30 mm, 32 mm, and 34 mm depending on the hub design.

Why axle nut size varies

Axle nut dimensions are determined by the hub design, bearing assembly, and the diameter of the axle shaft. Because hub assemblies and axle designs differ across car brands—from economy sedans to light trucks—the same model year can use different nut sizes, and some hubs use locking nuts or cotter pins that affect the head configuration.

How to find the correct size for your vehicle

To determine the exact axle nut size for your car or truck, use these steps:

1. Consult the owner’s manual or the vehicle’s service manual for the axle nut size or torque specification.


2. Inspect the nut or hub for markings, and measure the distance across the flats (AF) with a ruler or calipers to identify the hex size (for example, 30 mm).


3. If the nut isn’t accessible or markings are unclear, measure the axle shaft diameter and refer to a parts catalog or OEM documentation for the correct size.


4. Verify with a dealer or auto parts store using your vehicle’s make, model, year, and submodel to confirm the exact size and torque spec.

Ensuring you use the correct size helps prevent thread damage and improper wheel mounting.

Common sizes by vehicle type

Vehicle classes tend to fall into a few general size ranges, but exact specs are model-specific. Use the steps above to confirm the precise size for your vehicle.

• Passenger cars and many sedans: commonly 27 mm, 30 mm, or 32 mm across flats.


• Front-wheel-drive and some all-wheel-drive models: typically 30–32 mm, with occasional smaller sizes like 27–29 mm for compact cars.


• Light trucks, SUVs, and vans: frequently 34–36 mm across flats; some heavier-duty hubs go even larger.

These ranges are typical guides; always verify against your specific vehicle’s documentation or a trusted parts lookup.

How to measure the exact size on your vehicle

To ensure exact sizing, follow these steps to measure or confirm the axle nut size on your actual vehicle.

1. Park on a level surface, set the parking brake, and chock the wheels for safety.


2. Remove the wheel to expose the axle nut and any locking mechanism or cotter pin.


3. Place a metric or standard caliper on the hex and measure the distance across the flats (AF) to identify the size, or compare to a known nut.


4. Cross-check your measurement with the vehicle’s service information or a trusted parts catalog, and then apply the correct torque when reinstalling.

Using the correct nut size and torque keeps the wheel properly seated and prevents bearing preload issues.

Summary

Axle nut size is not universal; it varies by vehicle. Expect common across-flats sizes in the 27–36 mm range, but always verify with the specific model’s documentation or a parts lookup. When in doubt, consult a qualified mechanic or dealership to ensure you have the right size and torque specification for safe wheel mounting.

What size socket for wheel nuts?

The size of the socket for wheel nuts depends on the vehicle, but common metric sizes are 19mm, 21mm, or 22mm, which correspond to 3/4-inch or 7/8-inch sockets. To find the exact size, check your owner's manual or the sticker on the driver's side door jamb. It is important to use a socket specifically designed for impact use and that fits snugly to avoid damage and ensure proper torque.
 
How to find the right socket size

• Check the manual or door jamb: The most reliable way to determine the correct size is by looking in your owner's manual or checking the sticker on the driver's side door jamb or in the glove compartment. 
• Measure the lug nut: You can also measure the lug nut directly. Metric sizes like 19mm, 21mm, or 22mm are most common. 
• Know the imperial equivalents: Some vehicles may use imperial sizes. For example, 21mm is approximately 13/16 inches, and 22mm is approximately 7/8 inches. 

Important considerations

• Use impact sockets: Always use a socket specifically rated for impact use, as regular sockets can crack under the high torque of an impact wrench. 
• Ensure a snug fit: The socket should fit snugly to avoid rounding the corners of the lug nut, which can make it very difficult to remove. If a metric socket feels loose on an imperial lug nut (or vice versa), try the other size. 
• Choose the right drive size: A 1/2-inch drive is sufficient for most passenger vehicles and light trucks, while a 3/4-inch drive is used for larger or heavy-duty applications. 
• Use a torque wrench: When tightening the lug nuts, use a torque wrench to tighten them to the manufacturer's specifications to ensure safety. 

What size is a CV axle nut?

The CV axle nut size varies by vehicle, but common metric sizes are 32mm and 36mm, while some vehicles use 35mm, 30mm, or 39mm. The best way to determine the correct size is to measure the existing nut or check your vehicle's service manual. Alternatively, you can use an auto parts store that allows you to test sockets before purchasing.
 
Common sizes

• 32mm: A frequent size for many front-wheel drive vehicles.
• 36mm: Often used for front axles on some vehicles.
• 35mm: A common size for front axles on some vehicles.
• 30mm: Used on some vehicles.
• 39mm: A size found on some trucks, like certain Toyota models. 

How to find the correct size

• Measure: Use a digital caliper or micrometer to measure the nut's hex size accurately. 
• Check the service manual: Your vehicle's service manual will have the exact specifications. 
• Consult your new axle: If you are replacing the CV axle, the new nut that comes with it will have the correct size printed on it or you can test it against your socket. 
• Ask an auto parts store: Some stores will let you bring the nut to test sockets to find the right fit. 

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What size is the hub nut on a trailer axle?

Trailer hub nuts vary, but common sizes include lug nuts like 1/2"−201 / 2 " minus 201/2"−20, 9/16"−189 / 16 " minus 189/16"−18, and 5/8"−185 / 8 " minus 185/8"−18, which secure the wheel to the studs, and axle castle nuts like 1"−141 " minus 141"−14 or 3/4"−143 / 4 " minus 143/4"−14, which secure the hub and bearings to the spindle. The best way to determine the exact size needed is to measure your trailer's specific lug studs or axle spindle. 
Types of trailer hub nuts

• Lug nuts: These are the nuts that screw onto the wheel studs to hold the wheel onto the hub. 
  • Common sizes: 1/2"−201 / 2 " minus 201/2"−20, 9/16"−189 / 16 " minus 189/16"−18, and 5/8"−185 / 8 " minus 185/8"−18. 
  • How to measure: For lug nuts, you'll need to measure the diameter and thread pitch of the studs on your trailer's hub. 
• Spindle or castle nuts: These secure the hub assembly (including the bearings) to the spindle on the axle. 
  • Common sizes: 1"−141 " minus 141"−14 (very common for standard axles) and 3/4"−143 / 4 " minus 143/4"−14 (often found on older or smaller axles). 
  • How to measure: These nuts are sized by the diameter and thread pitch of the spindle they fit on. 

How to find the right size

1. Identify the nut: First, determine if you need a lug nut or an axle castle nut. 
2. Measure the component:
   • For a lug nut, measure the diameter of the lug stud and count the threads per inch. 
   • For an axle castle nut, measure the diameter of the spindle the nut threads onto. 
3. Purchase the correct nut: Use the measurements to find the correct nut size for your trailer. 

What size socket for axle nut?

The size of the socket for an axle nut varies by vehicle, but common sizes are 30mm, 32mm, 35mm, and 36mm. It is essential to check your vehicle's specific manual for the correct size, as it can differ between models and may have been changed if the axle has been replaced. 

• Common metric sizes: 30mm, 32mm, 33mm, 34mm, 35mm, and 36mm are frequently used, says JustAnswer, Reddit users, Parts Avatar, and Home Depot. 
• How to be sure: The most reliable method is to consult your car's owner's manual or a repair manual specific to your make and model to confirm the correct size and torque specifications. 
• Socket material: For high torque applications, such as loosening or tightening the axle nut, use a strong, impact-rated socket made from materials like chrome-molybdenum steel to avoid damage to the socket or the nut.