With the general trend nowadays being tubeless tires and 25-28mm widths, how do you know if an older wheelset is compatible? I have a TT bike that came with ~2012 Zipp 404’s and am getting a Colnago with ~2012 Campy Neutrons. How do I know if they will take either tubeless and/or wider tires?
Tubeless rims should say tubeless ready or something like that. The part where the bead hooks in in shaped differently, but it can be hard to see if you don’t know what you’re looking for.
Wider tyres - there is usually an optimal range for tyre width, depending on the inner rim width, but afaik most rims will be ok with 28s (maybe not super aero). However, the bigger problem for swapping to wider tyres is if there is enough clearance on your frame to take them.
Internal rim width will also effect the tire width. On my R3, 25mm Vittoria Corsa G+'s fit just fine on my Easton rims. Same tire mounted on my carbon rims with a wider internal rim width are no Bueno. I get tire rub in the rear.
Research. I’m not sure either of those are tubeless-compatible, though I could be wrong. You’ll just have to do some research on the specific wheel (year, make, and model) to find out the details. There’s no clear way to know just by looking at it.