Will these work as a direct replacement for my factory lug nuts?

Yes, as long as your vehicle uses M12 x 1.5 bolts. Thread pitch is the critical match — verify yours before ordering. Aluminum lug nuts are lighter but require the same torque spec as OEM, so reference your service manual for proper tightening.

Do these need any prep or painting before installation?

No prep required. Both black and green finishes ship ready to install. If you want a uniform color across all wheels, you'll need to paint or anodize the mismatched pieces separately.

How does the lock-nut feature work and do I need special tools to install them?

The lock-nut design uses friction inside the nut to resist loosening — no special tools needed. A standard socket and torque wrench is all you need. Hand-tight first, then torque to spec with your wrench.