I know I just gave these to Daniel and to Michael a while back and saw Tyler ask recently. Figured I would post the (slightly updated) plans for everyone and anyone to use or improve upon.
My main goal was to fit 8 275 tires/wheels on it. So many racks out there only allow 7. It's such a simple fix, and still within the legal 8'-6" width limit. Myself, Tilton, and Pranav all have tire racks of this design. The part I'm most proud of is that it can fit different trailer configurations. The legs can by placed anywhere along the main beams in any orientation and height. Tilton placed the front two legs along the front edge of the trailer to retain access to storage boxes. Mine are cut down fairly low to aid loading the tires, and bolted from the sides.
After looking at many trailers in the paddock, decided on the simple approach to retaining the wheels with the bar thru the centers. One complaint was that this method could damage the wheels especially if they are hub centric. My solution was to use conduit (instead of heavy pipe) with a pvc sleeve. Worked so far.
The idea we had for security was easily available locking hitch pins. I have just normal pins for when the trailer is in storage, and locking when tires are on the rack to save the locks from weather exposure.
The 1.00lb weight and barbell clamp does a decent job of keeping the wheels upright when using less than 8 wheels (or 8 wheels/tires narrower than 275's).
One addition I plan to add to mine (that isn't on the drawings) is a strip of ABS plastic on the beams under the tires so they don't rest directly on the steel.
http://www.fototime.com/D30C9EF28FD4EF9/standard.jpg
Link to full resolution file... http://www.fototime.com/D30C9EF28FD4EF9/orig.jpg
http://www.fototime.com/30D02F5416024CA/standard.jpg
Link to full resolution file... http://www.fototime.com/30D02F5416024CA/orig.jpg
.pdf format.
http://www.fototime.com/A86B56955898AED/orig.pdf
http://www.fototime.com/97EAD2E17D77A73/orig.pdf
