I have a 1994 4 Door Metro with the 1.0 litre engine with a 5 speed. I switched the 12" to 185/60 HR 14 on a 14" X 6" rim. If I were to do it over again I would search a little harder and go with a 185/55 HR 14. The 185/60's are a over a inch taller than the 155/12's and although I never have a problem with the tires rubbing ever the result of the taller tire has been to make the Metro even more gutless with a lower final drive ratio (higher geared).
But it did make a incredible difference in the way the car drives and handles. It is a really blast to drive now and handles sooo much better and is way safer than before. I would recommend this upgrade to any Metro owner, but like I said I would try and find 185/55 HR 14's as my first choice and 185/60 HR 14's as my second. Here is a link to the picture so you can see what it looks like.