These tires have a stiff side wall, that allows them to run lower pressures. Also they don’t weigh as much as a car so 35psi is not needed. Higher psi also offers greater fuel economy. With atv’s traction trumps fuel economy.
Almost all vehicles that are used where extreme traction is needed run low pressure in the tires. LP adds to the size of a tires footprint, also allows the tire to conform to the terrain or obsticle so the lugs have more contact.
Imagine a high pressure and low pressure tire sitting on a rock. The LP tire will sort of wrap around the rock and the HP tire might stay completely round and not offer as much surface of the tire to contact the rock.
They do make low pressure gauges but I generally use the foot push test to make sure both are somewhat equal and use my eyes to make suer the tire is not running too flat. Its a skill that will easily come to you when you know what 4 psi looks like.
Hope you enjoy the new meat. – Mark