Just got off the phone with rimguard the rear tires take 8.3 gallons and add 89pounds, then then I called the only dealer near me and it cost 3.50 a gallon to have it put in and that includes the rimguard. they didn't have a chart for the front tires but figured it takes between 3.5 to 4 gallons for the front tires that would add somewhere in the range of 37.5 to 44 pounds. I had a tire dealer give me a quote on doing the rears with calcium chloride and he said $150 per tire
think I will go with rimguard.