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You can use any wheel/tire combination you'd like for the front wheels, but as far as I know of the dually rear wheels are only avaible in the 6" wide, regardless of the 16", 19.5", and 22.5" wheels.
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Stock dually outside of tires is 94+". Going a little wider is possible, but around NJ they bust humps in the local towns if you obviously exceed 96". You can get away with 102s on the interstates. Also, diesel dually is self inspection here and are subject to on-road inspections, and don't want to give them obvious reason to pull us over. Check your local laws before you go too wide.