Originally Posted by nusslejj
Thanks ! I'll have to find someone who can change all 6 tires valve stems. Sounds like it will be expensive...
My 2012 came with the AirFlexx extensions. I also had to trim the ones on the outer dual tires so the valves would actuate with normal tire guage and fill chucks.
Of note, FR used a 135 degree metal extension on the outer duals to "point" the tire fill towards the outside, then added the AirFlexx extension. The 135 degree metal extensions are normal, aired extensions (the AirFlexx are airless extensions).
As noted above, I have tied the extensions to the wheel covers and the wheel covers to the wheels with wire ties. I do not like the extensions - particularly the ones with the metal 135 degree "U turn" added extensions- whipping around as I drive.
I used the above with the rubber "high pressure " (with a metal core) valve stems until I replaced the tires and found a place that had metal stems that would fit the Mercedes rims. I did not have any valve problems with the OEM tires. Not easy to find bolt-in metal stems that fit - the rims on our 2012 are too tight on the inside for the locking nut to fit and be properly tightened with most metal bolt-in valve stems.
I did have two of the rubber snap-in valves fail on my second set of tires, but not from the extensions- per the tire shops that replaced them, both were damaged on installation. Both failed "gracefully " - I measured slightly low pressure before driving. I lost confidence and sought out metal bolt-ins.