They will be worn to the point of letting water in. I replace then every second tyre change.
I can't verify that..
just saying I do pack(smear a finger load) of grease, behind said seal, and that precludes any water ingress to anything behind it.. I only replaced an "outer seal" on one C10 I owned, as a preventative P/M once, as I had a chewed up seal on the speedo gear side, from a stupidly and rapidly found mis install..so I did both.(the seal on the gear side, and also the wheel r/h side) When proper bearings are installed, and a goober of grease is layered over them and outer seal in place, its a hands off, totally sealed thing, and can be cleaned, and reinstalled the same way for the life of the bike.. I do polish and clean the r/h "wheel" spacer o.d., that the seal contacts, every time, and have no issue after that.