Have used Kleber Quadraxer before and found them to be superb. They are a genuine 4 seaons tyres with the mountain and snowflake symbol meaning they are certified for use in countries where winter tyres are mandatory. Actually in the process of putting a set on our recently acquired car, cost no more than mid range summer tyres and are just as quiet and long lasting.

I ran non run-flats on my BMW 118D and it was fine. The insurance company were happy provided that all 4 tyres matched i.e. all run flats or all non run flats. I found the ride to be better but that could have also been the simple fact the runflats were 17" and and the non run flats 16". As for the handling it did feel a little less solid than it was on run flats when you presed on but was still fine.