[s-cars] Lug Bolts

[A Tay]

Hi all,

My friendly local tire shop has discovered they have been using conical lug
bolts in the ball sockets of my winter wheels. (After 5 seasons of
switchovers)

They have switched to supposedly the correct ball style lug bolt.

My question is the ball size used on Audis a common size?  

The shop says they are all the same size but im hesitant to trust them on
this one.

Thanks

Aaron