Lego Valve Caps.

Genuine Lego brick Valve caps. The valve cap itself is plastic to avoid any damages to your valve. They come as a complete set of 4 can be used on your car, Bike etc. These are available in a large variety of colours and stand out very well. 

You don't have to stop at just a brick. You can actually add your favourite Lego characters, Or create a little build just ensure you glue it together if you want it to last.