I experience a hub failure this year at Sebring and my hubs only had approximately 10 hours on them, when it failed it snapped the axle and luckly the wheel did not exit the car before I got it stopped. After being put on a flat bed and brought back into the pits upon jacking the car the whole wheel assembly fell off. What Chris Childs told me was to check the torque on your hubs every session for two or three times and them make it pre race weekend check. The hub tends to back off and allows to much slack. But yes you need to change these every 12 hours of track time to be safe.