Tire Clearance Issues
When I put the Plus-sized tires on the old Motobecane frame, I knew that tire clearance was going to be something of an issue on the rear. The chainstays curve in very close to where the meat of the tire sits. The smaller diameter wheel, which allows the added height of the 3" cross-section tire moves the tire farther back in relation to the chainstays.
It helps that the frame has sliding dropouts, as that allows me to push the wheel farther forward. Unfortunately, the aluminum dropouts have been deformed, somewhat, under the fixing bolts. If you slide the axle forward, the bolt wants to work its way back into the depression in the dropout, moving the wheel back to the original location.
If you look at the drououts, from behind, there is plenty of room to drill new holes, and allow the wheel to move forward quite a bit more. I had planned on doing just this, until I realized that it really wouldn't work.
So, I did manage to get the maximum forward adjustment which is available with the droupouts, by torquing against the wheel with my foot as I tightened the bolts. Now, the wheel is as far forward as possible, but I have to trove the WR nut completely in order to get the axle past the rear derailleur pivot.
I suspect that there is a new frame in my future, but I am waiting to make sure that I put enough miles on the bike to justify the expense.
I sold my tubeless b+ wheel set and tires, over the weekend. Pretty much got back what I had in them. So, I was happy with that.