What lead to my being towed home?
So far both of my rear tire stems failed. We will find out about the fronts tomorrow.
The cause is a combination of issues.
The stem that caused my flat broke in two. Only the mushroom head remained in the tire but from there the Manager at Americas Tire was able to confirm that it was a Chinese stem which apparently should not be used.
The second stem upon inspection was going to fail soon as well. This was due to incorrect installation. Installation in the Factory Five wheels require extra attention. I am not the first to experience this and the response I received from my call to Factory Five is the same I found from another tech on a different thread.
The problem with the Factory Five wheels is that due to the lip thickness a recess is designed into the wheel to allow the stem to sit deeper in the lip so that the remaining thickness allows for a proper seat. The problem is that the recess in the rim is not wide enough. When the installer tries to install the stem in their normal fashion the mushroom portion tends to not seat properly. In fact, in my case part of the mushroom was pulled into the smaller opening creating a stress point.
For our wheels the installer needs to use the correct stem but also use plenty of lube during installation. It is also important for him to massage the mushroom head into the recess and make sure that it is properly seated. He may have to twist/rotate the stem to make sure that it is not partially pulled through the smaller opening.
At home I highly recommend that you gently pull the stem back and forth and inspect for any cracks and to see that it is actually seated properly. It is a really cheap fix compared to replacing tires and a tow.
This is the correct stem and also a picture of my wheel recess. I am also a bit concerned by how rough the opening is but I was told by Factory Five that this is normal.
The metal studs that were available at Americas Tire will not work. As is the problem with the rubber stems, the recess is not wide enough and will not let the metal stud seat properly.