Will these work on my factory wheels?

M12 x 1.25 is a standard metric thread pitch used on many vehicles, but your specific application depends on your wheel stud configuration. Double-check your vehicle's lug nut spec before ordering — wrong thread pitch won't seat properly.

Do I need to replace all 20 or just what I use?

You get 20 nuts — enough for four wheels with spares. Most wheel applications use four or five lugs per wheel depending on your setup. Use what you need and keep the rest as backups.

How tight should I torque these?

Refer to your vehicle's service manual for the correct torque specification. Over-tightening aluminum lug nuts can strip the threads; under-tightening risks wheel slip. Always use a torque wrench and follow manufacturer guidelines.