CHINA BOMBS Trail Express trailer damage

[Tdifrank]

I have a question that maybe you people can help with.The tire seperated and chewed up the bottom of my camper and wrapped itself around the axle cut wires to breaks. have since replaced the tires and rims went to a 6 inch wide wheel so i could use a better tire. when the tire came apart it almost caught on fire it burnt the plastic sheeting that is under the camper what is this material and what the best way to repair it so it does not leak and rott my floors