Thanks Dandeman,

Basicaly, I need to figure out what volume of air is needed to go from 10 to 20 psi for all four tires. Then, using the known volume of my rear bumper, I need to calculate what pressure the resultant volume required would end up at in said bumper. Finaly, as you stated, I then multiply that pressure by the area of my end caps to make sure I`m not exceeding safe limits. The only problem I can foresee is if the volume needed would result in a tank pressure that might be difficult to achieve with a regular compressor. I can set my shop compressor to 150 psi but what if I need 200 psi? I`m sure I could figure something out.

Toughguy