Originally Posted by
SoSmellyAir
Specialized says that its Roval Terra CL, which is hooked and has an internal width of 25 mm, can take 28 mm tires. Even that sounds a bit iffy to me.
Iffy in what way? Hooked is as safe as it gets for wired-on/clincher tires. Even back in the 1980's when a few companies were selling MTB rims with 19-mm internal width, the main concern was that tires over 2 inches in width, run at low pressure on single-track trails, might flop over sideways on high-speed turns, but they'd stay on the rim.