im looking for the thinnest 15 inch tyres, so i could possibly get some stretch on a set of trx wheels i have laying around..

you could go for space savers but they are speed rated to 80kms i have one that is 130/80/15 but you could go for something like a 165 or 155 if there is someone that still makes them !

maybe the same size as what would be on a holden fj or something ?,they have cheese cutters !!

I had my 165/50s on trx wheels and were pretty much flush sidewall,but then put them on my 7s and theyve got heaps of stretch
Need like a 145 to get any stretch on 5.5s

Nankang make a 145/65R15 72V. It is meant for a 4.5 inch rim but i couldn't imagine it lookings very streched. It is only slightly less tall than a 195/50/15. Apart from that you would have to start looking at front runner style tyres which would be getting quite tall in the profile.

Back in the day, Renault 10's had 135-15 tires, and they were pretty well always Michelins. I've seen a few of these cars in the last 10 years or so that look like they have tires that were made AFTER the 60's so perhaps they're still available. Pretty damn skinny - keep away from tram tracks or you might end up at the terminus!