You put too much importance on tires.

The speed and the way you drive is way more important.

I've never caused an accident and that's despite the fact that I've always driven on the cheapest tires I could get and only replaced them when they were either completely wore out or lived in a state where they wouldn't pass inspection.

I will never forget the time when I was coming home from work during a snow storm in the north-east and a guy whose just overtaken me in his somewhat new awd subaru spun out right in front of me. Yet my rwd benz on dry-rotted tires always got me home safely.