OK on our way to Redding ca from bullhead city first trip in this new to us MH 01 holiday Rambler 30'have 6 new ironman 255/70r 22.5 load rang h tires trying to find the chart that will give me the pressure to set the tires at had I weighed at the first scale we got to and the weight is 6660 on front ax. and 14740 on the back 21400 total can I use any chart or does it have to be Ironman cant seam to find a chart for them and how do I do the rear divide by 4 or what any help will be appreciated Thanks Gary