Tire valve w/tmps fails. this is a simple and very standard but critical component to maintaining tire air pressure. the valve broke off in the simple act of removing the cap to add air. break was the end of the valve stem and prevent airing the tire. the hyundai dealership service department inspected all wheels and found two more caps which they refused to try to loosen since they were out of valves to replace. this service department seemed to recognize their effort would likely have same result. they seemed to know this is a problem. a quick internet search shows this to be a common experience. the ability to pressurize the tire is a routine maintenance task which must have robust tire valve, since tire pressure is critical safety requirement. the typical user is very use to removing a tire valve cap and not have a problem. the valve design being used by hyundai appears to be common design for many models/years. this is a very serious problem with a design for a critical safety component. this needs to be investigated and immediate corrective action taken. *tr