View attachment 936754
I figured I'd update this post with my modifications that make the Yakima Holdup work with the 4.6 tires on my Fatboy. I followed the above posts to remove the plastic cover for the main hoop. Then I also pulled the metal hoop off the rack and used a spreader in the lower portion of the hoop while keeping the end cap areas clamped in a vice to keep them from opening up as well. I gained about 1/4-1/2" additional clearance in the metal hoop and the plastic still slides over just fine. Obviously this step is a little more advanced, but it yielded good results.
I also cut down the plastic tire retainer that holds the rear of the tire. I could go back and shave it a bit more to get a better overall fit, but for now it works fine and retains plenty of usability for non-fat tires.
Another tip is to pull the c-clip and pin from the metal locking pin at the top of the locking arm assembly and replace it with a 3/8"x2.5"
PTO Pin that I picked up from Menards. This allows you to pull the top cap and ratchet portion off the arm quickly so you can rotate the arm over the tire and then put it back on to lock it down in place. I'm still using a cheap nylon utility strap for the rear hold down, but I may do the homemade extension shown above.
The tires are still a tight squeeze, but even with 13-15 lbs of pressure, I can use my hand to push it down far enough to get the tire in metal hoop enough to lock it securely in place with the arm. The bike and rack just got a nice 2200 mile test out to Colorado and back and worked great.