Polo Wheels (Tyres, Spokes & Rims)

Would be handy if you can find the actual external width somewhere. You should be ok to run any tyre that's equal to/greater than the exterior rim width, it seems quite popular to run 23c on 23mm rims is quite popular at the moment. Example is Velocity's marketing blurb:

With a wider footprint, the A23 allows for a more aerodynamic rim/tire combination when paired with a 23c tire. The tire profile mimics the characteristics of a tubular, gaining increased control and lower rolling resistance without the inconvenience of tubular glue or the dangers of irreparable roadside mechanicals.

Admittedly the ETRTO guidelines suggest you should run 37c on something with a 23mm interior width, but that was from 2007 or so.