What is the rim width?

Pretty sure that is a Zipp 900 clincher, not a Sub9.


I'll let others answer which tyre as that depends on a myriad of things.

Sub9 was only tubular, thats an R900 clincher: https://www.zipp.com/wheels/900-clincher/

Max Width at the brake track is 24.85mm, so you want a 21-23mm tire. The Vittoria Corsa Speed TLR is likely your best bet, or the new 23mm Conti 5000 depending how wide it measures