I'm torn between getting some winters to run for a few months or getting some less extreme summer tyres like the Michelins. I still have 5mm left on my Corsas after 10k.
difficult. The corsas are very special when the weather is right and they have been warmed up, but are very un-special when it's not. I've had plenty of instances (outside of the cold months) where the tyres weren't warm enough and I had a moment. They need heat to grip and town/motorway doesn't generate it, even in the summer. If you only do fast driving then it may be worth the ball-ache of switching tyres twice a year, but if not I'd switch the out for something more flexible. Whatever you do, don't be tempted to stretch out the corsas for much longer.