I've used Armour-All on my tires and many other things for years for UV protection and shine. My current RV tires are now 10 years old and not 1 sidewall crack on any of them. Many use 303 Protectant which is good stuff. Of course regardless of looks, 10 years is over the recommended replacement time and I'm taking a chance. Some think this is bad for tires, so they use covers.
Nitrogen - to me is a bunch of BS. Air itself is 79% nitrogen. So 21% more is a miracle?
Keeping Jacks down probably helps some. I don't do it in long term outside storage because of jack shafts rusting. Of course treating them with lithium grease would cure that, but then you get dirt stuck to them
, so I just don't do it.
I'm sure I will be shot at over my way to do things, but my Jap tires are 10 years old.