Rear tire going flat

[NorthPole]

My second annoyance with my new 3520. Last month when I started to move snow the LH rear tire (43" R4 mounted with the stem on the inside) all but went flat. I got into the garage where I could work on it with some heat and a compressor. At one point, the brass fitting that holds the Schrader valve came loose. I hadn't realized there was more than on piece on the stem. Okay, I tightened it up, inflated the tire. cleared snow for a couple of hours without any problems (tire or fuel if you've read my other thread). Put the machine way. Mother nature decides to snow again. No worries, plug in the tractor for a couple of hours, fire her up and the tire is neigh on flat again. Again, inflate it, have no problems.
Today, it is completely flat I find out when I lift the ballast box and FEL. Carry out a floor jack and air compressor, take the brass fitting out of the stem, put a bit of Teflon tape on it, put it back in, snug it up, inflate it. Then had so many problems with tractor stalling out, I put it way.

Are there known problems with these stems? I've not found any leak in the tire itself.

 

[Tx Jim]

The removal tube stems I've seen have an o-ring on them. Does yours? If so I'd suggest to R&R o-ring.

 

[NorthPole]

The removal tube stems I've seen have an o-ring on them. Does yours? If so I'd suggest to R&R o-ring.

There is an o-ring. Not having one that size, I replaced the Schrader valve and put some Teflon tape on the fitting. 24 hours and it seems to be holding. Next summer, I'll R2 the o-ring.

Thanks