Tire stretching is wrong and not recommended. For 8jj wide rims you need to use minimum 215 wide tires and even that already start to stretch just a bit but still within the max limit tolerance. For 185 tires, max just use 6.5jj rims. So in summary you've bought the wrong rim size for your car, so better change it again.

You mean having your 8jj rims for your Saga, or having 185 tires on 8jj rims?

Actually as long as the rims/tires (provided you use properly matched tire size) are not touching anything else on your car but yet stay within the fender/body line, then still ok, but the question is can they? 

Can be a bit more actually but not much longer. You need to start paying careful attention to the sidewall if got signs of cracking, especially since we're driving in hot & humid condition. Coz I've used tires up to about 5yrs before and when I changed it, the sidewall rubber suddenly crumbles into pieces when they're taken off/pressed by the machine. It was quite an eye opener for me because just a few weeks earlier I still took that tires to about 180-200kph!

Yeah, I was shocked and relieved at the same time back then. The problem was, we never see the inner side wall, always only the outer side that we clean and put tire polisher. All that time the inner side become brittle and developed cracks which all crumbled during uninstalling process.