in stand rear escort guards what is the largest width wheels people have fitted as i found a great set of 16x9 -13 offset i would love to fit in the car just wonderign if im going to need to mini-tub the rear of the car to get them in there...

Would be amazed if they fit. 
 
Arches would be much, much easier than mini tubbing given you'd have to shorten axle assembly

13x7 +6 are tight with folded lip on a std axle width, you are talking  another 1/4" wider outside offset, 1 3/4" inside offset - dunno if that would squeeze in.
 

A 16 x 9" -13 has the same backspace as the fairly common (13, 15, whatever) x 7" +12, namely 114mm or 4.5", so all that extra width is going to get pushed out, increasing your track.  With numbers like that I'd say you'd need to install arches for sure.

my rear axle is shortened borg warner diff. only 1300 wide i think stand escort is around 1365 or similar?? im going to arch the car anyway... was hopimg to avoid it right away though

1300mm wide vs std 1350mm = extra inch of outer clearance each side. Based on that and my own experiences, and provided you roll/fold the guard lip, the outer clearance is potentially doable. The concern becomes inner guard clearance - you would be using equivelent of 5.5" backspace. I have not run wheels with a backspace that high - perhaps someone else has and can answer regarding inner guard clearance?