I'd probably say around 5000km's. They would be fairly hard km's as most would be at the track, drags, powercruise motorkhanas etc. I have a work car that I drive most of the time.
I don't think that the cracks 'battery' has would cause the wheel to fail, they are not at a stress point (as far as I can tell). For all I know mine has been cracked the whole time as well