Ok how do i do this, its for my 2011 5 spot. It takes 2 short countersunk bolts but i cant find any info on the net for them.

I use the 15 quid hangers from CRC but these come without the bolts and i am sure these would be easy enough to ID if i knew the corresponding measurements.

is it outside or the inside of the threads that determine the thickness?

Ta

do you have any of the screws? It is the outside of the screw thread as the screw is cut from a rod of the correct diameter – ie M5 thread cut onto a 5mm dia bar. The female thread is cut into an undersized hole.

Yep, i have 2 already on the bike but no spares, that makes sense TBH.

Ill measure tomorrow and have a search online 😀

As well as the OD, try and measure the pitch of the thread, you also get fine pitch versions of metric threads.