Bill,
Weigh each axle of the Big Sky (if you can, weigh each tire...it's good information about loading) when hooked up to your TV. Go to the tire manufacturer and look for inflation tables for your tire. If you have the goodyears, the website is
http://www.goodyear.com/rv/pdf/rv_inflation.pdf
Do not automatically pressure the tires to the maximum listed on the sidewall, but fill them based on the load they'll carry. Some manufacturers will give you about a 10 psi overinflation, as long as you don't exceed the maximum, either for the tire or rim, for decreased rolling resistance. G load-rated tires will give you a margin of safety that E rated tires don't, but don't use it up by overinflating.
Bob