What size socket goes on a lug nut?
Typically, lug nuts require a 19mm or 21mm socket, though some vehicles use 17mm or 22mm. The exact size depends on the car, so always check the owner’s manual or measure the lug nut flats to confirm.
Common Lug Nut Socket Sizes
Lug nuts come in a few standard hex sizes. The list below covers the sizes you’re most likely to encounter on passenger cars, light trucks, and SUVs.
- 17 mm
- 19 mm
- 21 mm
- 22 mm
Note that some vehicles use non-metric sizes or unusual patterns, and some wheels employ 12-point fasteners instead of the standard hex. When in doubt, verify the exact specification for your vehicle model.
Common variations you may encounter
While 17–22 mm covers the majority of scenarios, a few exceptions exist. Many European cars and certain SUVs favor 21 mm, while some trucks and larger vehicles use 22 mm. If you’re unsure, refer to the owner’s manual or measure the lug nut across the flats to identify the correct size.
How to Determine the Correct Socket Size
To avoid rounding or damaging lug nuts, follow these steps to confirm the right socket size for your vehicle.
- Check the vehicle’s owner manual or a repair guide for the specified lug nut size.
- Inspect the lug nut flats and measure the distance across two opposite flat sides with a caliper or ruler. Compare the measurement to standard sizes (17, 19, 21, 22 mm).
- Test-fit sockets starting with the most common sizes (19 mm and 21 mm). The correct size should slide on with minimal play and no slipping. Do not force a socket onto a lug nut.
- Note the lug nut type. Most are 6-point hex; some OEMs use 12-point or non-standard shapes. Use the appropriate 6-point socket to maximize grip and minimize rounding.
- After installing or removing a wheel, torque the lug nuts to the manufacturer’s specification with a torque wrench. If you don’t have the spec, many passenger cars fall in the range of 80–100 ft-lbs, with higher values common on some trucks and SUVs.
If you still can’t identify the size by inspection, consider bringing the vehicle to a shop or consulting model-specific torque and size charts for your exact year and trim.
Safety and maintenance tips
Always work on a flat, stable surface with the parking brake applied. Use wheel chocks on the opposite wheel. When removing lug nuts, use a breaker bar or impact tool with care and avoid striking the wheel or studs. Re-torque to spec after a short drive to ensure the wheel seats properly.
Summary
In practice, lug nut sockets most often come in 19 mm or 21 mm sizes, with 17 mm and 22 mm appearing on some models. To identify the correct size, consult the vehicle’s manual, measure across the lug nut flats, or try sockets from the common sizes until one fits snugly. Always use the proper socket, a reliable torque wrench, and follow manufacturer specifications for safe wheel mounting.
