A hubcap for a wheel end assembly of a heavy-duty vehicle seals an outboard end of the wheel end assembly. The wheel end assembly includes a wheel hub formed with a cavity that contains lubricant, and the hubcap positively engages and mounts on the outboard end of the wheel hub to prevent the escape of lubricant and the ingress of contaminants. The integrally-formed hubcap includes a generally cylindrical sidewall and an outboard wall that extends generally perpendicular to the sidewall. A lip extends inboardly from and a shoulder extends radially outwardly from an inboard end of the sidewall, and the lip and shoulder cooperate to positively mechanically engage the outboard end of the wheel hub. An O-ring is disposed between the lip and the wheel hub to provide a seal. The hubcap also is adapted to accommodate components of a tire inflation system and other auxiliary components.