In Utah, particularly the PaiuteTrail System the 50" gates are definitely no wider than 51". Different wider tires and wheel offsets on a P500 will most always not fit. Spent 3 weeks there in 2012 on a showroom stock 50" RZR then another week in 2018 on a Pioneer. At this particular 3 million acre trail system there are 50" & 60" gates on certain trails, clearly marked on all the maps with usually a non width restriction go around.
That said all the best trails there are behind the 50" gates but definitely worth going once for the scenery on any size machine.