Will these fit my vehicle?

M12x1.25 is a metric thread common on European cars and imports. Verify your current lug nut size before ordering — thread pitch and diameter must match exactly or the nuts won't seat properly.

Do I need to replace all 20 at once?

Yes. This set gives you five complete wheels' worth. If you're matching a single wheel, you'll have spares, which is actually useful for replacements or future wheel swaps.

Can I tighten these by hand or do I need a torque wrench?

Use a torque wrench and refer to your vehicle's service manual for the correct specification. Hand-tight is not enough — wheel studs must be torqued to factory spec to ensure safety and prevent vibration or loosening.