A couple of mates have some experience of Cooper. Both live in NT, so their driving is both high speed and off road.
In the first case, a left rear let go (very much like the picture above) whilst on the highway. Part of the debris jammed the handbrake on, and that caused the car to roll multiple times.
The second bloke had two events. In the first, an almost new Cooper was on a 4wd (a Troopy) towing a trailer carrying a bunch of quads. Tyre let go, and took the vehicle off the road. Thankfully didn’t hit anything solid, and stayed upright. I was being told this story, as we travelled in a Land Cruiser, and going past the spot had been the reminder to tell me the tale. Within a few minutes of the story ending, vibration from the front of the LC, which was rapidly getting worse. Pull over, and yet another newish Cooper was in the process of failing. He had all of his vehicles reshod as soon as it could be arranged.
In no case did they stand by their warranty.