Maybe a fun thing to figure out for all you SCUBA-divers out there ...

I've always been curious of the weight carrying potential of a fully inflated passenger car tire. Said another way, I've wondered how much steel/iron weight I could hang from a floating passenger car tire (wheel included of course) before it starts to sink.

It has always seemed to me that four inflated tires would provide a tremendous amount of bouyancy, thus the tendency for vehicles to be more bouyant that one would think given their dry weight.