I run 650A/590mm tires on my Raleigh 3-speed. The main disadvantage is a dearth of high-quality tires in that size. The Panaracer "Col de la Vie" is probably the best, and that's largely because the other offerings are quite mediocre. The Col de la Vie has a fairly supple sidewall, like the Pasela, but the tread is thicker than the Pasela. They're wider thasan most other 650A tires, and take a bit of care to ensure mudguard clearance.