I need some lug nuts for my truck, I know they are 5/8 but does anyone know the thread pitch?

 

5/8" - 18. I'm having a tough time finding some for my truck. All the local parts stores and shops can only find 9/16" anymore. The only place I found the 5/8" 2-piece lug nuts is Southwest Wheel Company. I'm debating if I want to spend the $4 each for a full set and $22 for shipping but since they're the only place I can find them, I may have to.

This is why I need some. This one couldn't hold up to 300ft. lbs.