Physics

Hey Im new here but I see tons of posts where people are adding air pressure to help float tires. I’m sorry but this makes no sense to me. Floating is about how much water you displace vs the weight of what you displaced it with. 1 cubic foot of atmosphere at sea level weighs 1.3 grams. So the more air you stuff in a tire, the more it will weigh, and the less it will want to float. Think of a full oxygen cylinder with 2000 psi in it…it hardly floats at all. The optimal float pressure would be whatever pressure the tire stops stretching in size and juse starts cimpressing the air. My guess would be around 7 to 9 maybe. Or am I totally wrong???