Wow, thanks for all the replies. Re the speed: At the time, traffic conditions were limiting speed to 60 mph. However I generally drive at 62 - 65 mph as measured by my gps. The tire is supposed to be rated for this speed. If that counts as abuse, then I am guilty as charged.
Re the propane lines in the photos: Yes, you can see two on the passenger side and there's another on the driver's side. Basically, they chose to run the lines only in the most vulnerable spots. A true marvel of engineering, as someone stated. Only luck prevented them from being torn out.
I don't think upgrading to 15" wheels and tires is an option, but if the Kumho tires are a better 14" option, I'll definitely have a look.
There was some discussion about the construction of the Maxxis tire, whether or not it has a cap ply. I would be happy to take more closeup photos to answer this, but I'm not quite sure what it means.