stretch is just putting a really skinny tyre on a particular sized wheel (ive got 225s on my 9.5s and that isnt that much of a stretch, but I had 195s on 10s on one of my Volvos, THAT is a stretch ), and a skinny one for something that narrow would be a 2CV tyre and would be like driving on ice, lol.

Some spacers wouldnt be a bad call tho, 30mm and some mild plastic arch trimming if it was me.