Will these work with my current wheels or only aftermarket?

Extended lug nuts work with any wheel — stock or custom. The extra 60mm length is designed for wheels pushed further out via spacers or offset rims. If your wheels sit flush or close to the hub, standard nuts work fine, but these won't hurt anything.

Do I need to replace all twenty at once?

Yes, buy this set as a complete replacement for all five wheel positions (four wheels plus one spare). Mixing nut types or heights across your vehicle creates uneven clamping pressure and handling issues.

What's the torque spec for installation?

Refer to your vehicle's service manual for the correct torque value. Aluminum nuts don't change the spec — only the application method. Tighten in a star or cross pattern, then double-check after your first drive.