A few years ago I was at a motel on Route 66 on my old Valkyrie. I talked to a guy riding a GL1800 who was running a Valkyrie rear tire (180/70-16) in place of the Wing's usual 180/60x16. Depending on the brand, the 70 series tire is about 3/4 of an inch taller, giving you almost a half inch of extra ground clearance in the rear.
Has anyone tried this? Even with the rear suspension dialed up I scrape my pegs easier than I like, so a bit of extra clearance might be a good thing. The 70 series tire is easier to mount, too. I know as I've put dozens on my 2 old Valkyries.