Originally Posted by yankeefan

622 x 16 is the right info. Its a narrow box section wheel, which is an odd choice for a modern road bike but I suspect that its due to the fact that you're running disc brakes and/or specialized wanted to equip it [the bike] with a more versatile wheelset for light off-road use. The "standard" internal width for road wheels is usually 19, but wider widths are slowly becoming de facto. 25mm will be fine, but I doubt it will make you feel any racier unless you get one with low rolling resistance. I personally run and enjoy Schwalbe one tubeless, and I suspect that their non-tubeless version will be almost as good. GP 4000 IIs tend to be very popular around here, but they cost a pretty penny unless you import it from the UK. I've never used them myself so I can't comment much on the quality.