I was running rigid steel singlespeed in a 24hr (4x) and want some cush so put a Tioga DH tyre on the front of the VERY cheap wheel. Back then I didn't understand anything about Crr or tyre sidewalls, etc so it was probably worse than just fitting a skinny XC tyre.
2.5? I thought it was all 1.95" when you dinosaurs were starting out. Isn't 2.5 plus size any more? It's modern no? I don't know any more