Original MGA wheels have 5/8-inch hole in the wheels for the valve stem. Many currently available tire tubes have smaller valve stem that is not directly suitable for the larger hole. For this you need the valve stem bushing to install in the 5/8-inch hole from the inside before installing the tube. These may be available at any local auto parts store. If not you should be able to find them on eBay. -- tire+tube+valve+stem+bushing