I've said it before and I will say it again for those new to the site or who choose to not listen.

The rubber stabilizers or whatever they are called will not prevent the sudden loss of air due to a failure of the valve stem extensions. The extensions are for those folks who choose to not use a long straight foot tire fill valve. They being the valve stem to the outside dual. The rubber grommets are supposed to hold the valve stem extension so the centrifigal force from wheel rotation does not cause faitigue failure of the valve stem where it comes from the wheel and makes a 90 degree turn.

I knew about the extensions being opposed by Prevost in the early days and did not use them on the first coach. My current coach had the grommets and extensions and because I was lazy I did not remove them or the extensions.

Prevost Maintenance 016.jpg

When I did get around to seeing what was what this is what the extension looked like. Road dirt and grit gets between the rubber and the extension and it wears the extension. But in case anyone wants to think the grommet prevents flexing of the stem and faitugue failure Roger and I were shocked to see his extensions had worn a groove in his Balancemasters and the extensions and he was only a short time aways from a sudden failure of the extension.

Prevost Maintenance 023.jpg

I now use the fill valve with the red hose shown above for filling. My valve stem caps are the fill through the cap type.

Unfortunately the trade off is I cannot and will not use tire pressure monitoring systems that require the use of valve stem extensions because of the problem shown in the first photo.