SKF introduces four new PSI compatible hubcaps to its premium wheel end Scotseal product offering. The new hubcaps are compatible with the Meritor Tire Inflation System (MTIS) by Pressure Systems Incorporated (PSI), an automatic tire inflation system (ATIS). MTIS uses compressed air from a trailer's air system to inflate any tire that falls below a specified pre-set pressure. The system ultimately increases tire life, fuel efficiency and safety.