Will these fit my wheel studs?

M12x1.25 is the most common thread pitch for domestic trucks and sedans. Check your vehicle's lug nut specification before ordering — thread pitch must match exactly or the nut won't seat properly.

Do I need to replace all 20 at once?

You only need four to five per wheel depending on your vehicle. The 20-piece set gives you a full replacement set plus spares for future wheel changes or lost nuts.

Can I hand-tighten these or do I need a wrench?

The knurled design helps with hand grip, but you should finish tightening with a socket wrench to the torque specification in your vehicle's service manual. Hand-tightening alone won't secure the wheel safely.