One time some years back when this fatigue failure mode came up on RAS I asked Mark Mocho about it. He created an external spare wheel mount on the side of the trailer, just in front of or closely behind the wheel (can't recall which). Put on a cover to keep the sun off the tire. Worked well.
Don't have it on present Cobra, though perhaps should.
Ask Mocho at M&M Fabrication.
HL.





On Sunday, September 20, 2009 at 11:56:12 AM UTC-6, Barny wrote:
Just a warning to check your trailer spare before a trip and along the
way at gas stops. My 1998 trailer spare tire mount broke on a highway
trip. The wheel is mounted on the frame that holds the glider nose in
place. Two 8mm bolts welded to the nose cone frame hold the wheel to
the frame. One bolt sheared and the other broke away at one of the
welds. I was extremely lucky that the wheel didn't go through the
canopy or damage a wing. The wheel was dangling on the remaining bolt
with the broken weld, the tire tread was 5mm from the wing. It didn't
touch the wing or canopy, so I was "spared" a horrific tragedy.
I had a small shop weld two new 8mm bolts in place. I then added a
third mount to the Cobra design to keep the wheel from rocking on the
existing mount. I suspect the wheel weight rocking caused the
failure. The third leg is very easy to make and install yourself.
Use a small metal bar from a home improvement store, two bolts,
washers and nuts. Photos of the broken mount and new third leg can be
seen he
http://www.flickr.com/photos/brucebarnard/