I actually started the build around using a spindle and bought the spindle and bearings. After looking at various designs and talking to Ransil who told me he had seen one of the spindles snap I decided to go the heim joint route. I don't plan on putting enough stress on the carrier to damage it but you never know. The other consideration was being able to adjust it. Once the spindle and carrier are welded in they really can't be adjusted much, especially if it moves a little under the weight of the tire. I'll have the ability to spin the joints 1/2 turn at a time to adjust if needed.
The joints are 3/4 - 16 thread with a 3/4 bore for a grade 8 3/4" bolt, others I have seen appear to be 5/8. The heim joints I picked up at Summit
http://www.summitracing.com/parts/CEE-6162/ are rated for over 23,000 lbs. Assuming the carrier weighs 40# and the tire weighs 90# and that weight is applied at a distance of approx 30" from the pivot the effective weight would be 130# x 30" long / 3.5" high = 1114 # on the heim, if the latch works well to secure the other end there shouldn't be any dynamic load but even if there was and it was 3x the static load there would still be a pretty good factor of safety. At least it sounds good... We'll see, I'm almost ready to put it together and I plan on standing on it to see how much it may sag so I can plan the latch and keeper accordingly.
The cut out was challenging but I wanted to do something kind of unique and my goal was to keep the tire centered on the body without obstructing too much of the view and keeping it tucked in as close to the gate as possible. I'm also thinking of mounting a Jerry can to the right of the tire. Thanks for the feedback, and hey what do you think for a finish. I'm thinking of Herculiner for the bumper and Por-15 for the carrier portion, but I'm also considering powder coating, any thoughts?
