Do these fit my factory wheels?

These are M12 x 1.5 thread pitch — verify your wheel center bore accepts M12 studs and that your wheels do not have pre-installed lug nuts that will interfere with the 60mm spike height. Test-fit one nut before committing all 20.

Do I need to grease or prep these before installation?

Aluminum can seize if installed dry. Apply a thin coat of anti-seize compound to the threads before torque. Refer to your vehicle's service manual for the correct torque specification — do not overtighten.

Will these stay black or do they tarnish?

Black anodize will age naturally over time and with exposure to salt, brake dust, and weather. Occasional cleaning keeps them looking fresh; if deep oxidation occurs, they can be re-anodized or replaced.