You guys are right as to 185 55's being fitted as standard although 195 50's were offered as an upgrade.
Offered as an upgrade by who? The factory? The dealers? Or are you on about aftermarket?
It seems funny looking back. There was a lad in the next village that had an RS1600i in about 1984/5. His new fangled 195-50-15's looked massive compared to our dad's 155 R 13's on their Marina's and the like. Nowadays they look so tiny.
