Puzzle - 56

A man was travelling back home from work on the highway in his car and suddenly he noticed that one of his car's tyre got punctured. So, he stopped his car on the pavement along the highway and replacing the punctured wheel. While picking back the nuts to tight the spare tyre accidently he drops all the nuts into the deep drain and loses all four of them. He doesn't have any more spare nuts even to tighten the tyre. A passerby gives him a piece of advise, with which he drove his car back. What was that piece of advise?