I like the ripsaws, on my 3rd set. My 27's just barely kiss the front shock reservoir on fast and very bumpy trails The lowest I go is about 12psi because of all the rocks, without tracks I add air for additional GC for mud and snow. Too low of air pressure will increase you odds for pinch flats. I hope your 28s continue to work for you. Fully loaded we are talking about 2000 # on some models.