The Hobbit and Why the Car Didn't Melt

Everything is very simple: the melting temperature of gold is 1064,18 ° C and the melting temperature of steel is 1450-1520 ° C (I do not know the melting temperature of the dwarf). So we get the difference of about 400 degrees. In addition, steel with a high carbon content has very poor thermal conductivity, so the wheelchair could be covered with sludge (residual product of the melting of metal) also having poor thermal conductivity, so it does not burn!

No magic, I hope the question is exhausted.