Just a FYI, big changes to air pressure can also change mower deck slope.
I run 5 to 6 PSI in my rear and same in front..the tires are just about to belly out a little,,holds the slopes alot better and the ride is great!!
Any lower than 5 PSI I think would start to effect cut quality on my machine by bouncing out.
I am going to cut grooves in all my treads also..I did one side other day and that side holds the banks really well when its on the downside.