What is the size of the original bolts on a 2005 Impreza Widetrack STi?

I know they're 12x1.25 but what is the length?

Reason I'm asking is because I want to fit 20mm spacers so I need to workout the length of the new lugs I'll need to fit.

 

Do I just need to measure my current bolts, then add the size of the spacer to that, and that's the size bolts I'll need?

 

Nevermind, buying hubcentric spacers that go over the studs.

 

The nuts have nothing to do with it. You will need longer studs

 

Nah, I won't need longer studs unless I was fitting a 50mm spacer.

20mm is fine chaps