What size thread is a wheel stud?
There isn’t a single universal wheel-stud thread size. Most modern passenger cars use metric studs (commonly around M12 or M14 with pitches such as 1.5 or 1.25), while many American vehicles historically use imperial sizes (such as 1/2-20 or 9/16-18). The exact size depends on your vehicle’s hub design and lug-nut compatibility.
Wheel studs are sized to match the lug nuts and the wheel hub they fasten. Because models and markets vary, the only reliable way to know your vehicle’s wheel-stud size is to check the owner’s manual or a parts catalog, or to measure the stud directly with calipers and a thread gauge.
Common sizes you may encounter
This list highlights typical metric and imperial wheel-stud sizes found on passenger cars, light trucks, and SUVs. It is not exhaustive; model-year and regional variations exist.
- Metric sizes
- M12 x 1.5: The most common modern passenger-car stud size (used on many Asian and European models).
- M12 x 1.25: Used on a subset of models with a slightly finer thread.
- M14 x 1.5: Found on some larger vehicles and certain European brands.
- Imperial sizes
- 1/2-20 UNC: Common on many older American cars and some light trucks.
- 9/16-18 UNC: Found on some larger vehicles or specific trims; less common but important to verify.
In practice, the exact size varies by model and year; always verify for your vehicle before buying replacements.
How to identify your wheel stud size
To determine the correct wheel-stud size, use a combination of reference sources and measurement tools. The following steps will help you identify the right size and avoid incompatible lug nuts.
- Check the vehicle’s owner’s manual, service manual, or the manufacturer’s specifications for wheel-stud size and lug-nut size.
- Measure the diameter of the stud with calipers to determine the major diameter (e.g., roughly 12 mm or 14 mm, or the nearest fraction in inches).
- Determine the thread pitch: for metric sizes, a thread gauge can reveal the pitch (for example 1.5 or 1.25). For imperial sizes, count threads per inch (TPI) to identify 20 TPI (1/2-20) or 18 TPI (9/16-18).
- Measure the lug-nut seat type and ensure the lug nut matches the stud size and seat (conical/tapered, ball seat, or spline).
- If replacing studs, confirm the required length and chamfer to avoid interference with the wheel or caliper components; consult a professional if unsure.
Knowing the correct size ensures safe wheel mounting and proper lug-nut torque. When in doubt, consult a dealership or a trusted auto shop.
Practical tips for maintenance and replacements
When replacing studs or wheels, use high-quality parts and follow the manufacturer’s torque specifications. If you switch wheels seasonally, keep a small set of lug nuts that fit the vehicle’s thread and seat type, and always re-torque after initial driving to seat everything properly.
Summary
The thread size of a wheel stud is not universal. Most modern cars use metric sizes (commonly M12 or M14 with pitches around 1.5 or 1.25), while some American vehicles use imperial sizes (such as 1/2-20 or 9/16-18). Always verify for your specific vehicle by consulting the manual, a parts catalog, or measuring the stud and lug nuts. Accurate sizing is essential for safe wheel mounting and correct lug-nut torque.
