Will these fit my stock wheels, or are they only for custom rims?

The extended 44mm length is designed for wheels with deeper wells or larger offsets — typical of most aftermarket setups. Test-fit one on a wheel before committing the full set; if your stock wheels have shallow pockets, the extended cap may protrude beyond the rim surface.

Do I need a special socket to install these, or will my regular lug socket work?

Standard 19mm or 21mm sockets will fit the acorn cap. The knurled grip makes them easier to start by hand, which can reduce the need for repeated socket adjustments during installation.

Can I reuse the stock lug nut studs, or do I need new ones?

These are lug nuts only — they thread onto existing wheel studs. Your current studs will work as long as they're in good condition and match M12x1.5 specifications. Inspect studs for damage or corrosion before installation.