for the last 2 months i've had a flat on my drivers side rear of my truck. its a dually (dump truck), and i've been able to get away with until i had time. today i went out, and the other was flat (same side, other tire). so i take both off and go have 2 new tires put on. turns out, there was tubes inside. now i'm stuck there, with no valves cuz they don't carry any heavy duty enough. the guy sent me to about 6 stores asking. nothing. so we found a place that supplies 16" tubes, and 40 dollars alter the tubes were being put in. I was reluctant to use the tubes out of fear they would rip where the valve goes through the rim, but i had no choice today. which do you think would be better on a dump truck? the vavles (heavy duty) or the tubes? the guy was telling me the tubes were better, but i'm not sure if he was blowing smoke.. and does any one know where to purchase those heavy duty valves.. the metal ones that get bolted on? thanks.