texas addtion center cap screw size

Hi all,
Does anyone know the screw size to these Center caps. I fitted them at lows as 1/4, 20 x30.
But whne I go to put them on they are too big. weird enough though The originals fit but not the new ones.

 

That's probably metric

 

I thought so too, but that would be too easy

 

They're a weird size. M6x1.25 thread pitch which is hard to find in a M6 socket cap allen.

I'm currently trying to locate a couple myself