Bought a cheap second hand van, looked alright, tyres ok etc.
One of the tyres was a car tyre! Not rated for commercial use so has a smaller load rating, had it blown out and caused a crash I would be liable, possibly for manslaughter. The tyre looked identical to the others. The way to tell is look for the telltale letter C it should have. IE 185/65/R14C
Lugging 500litres of water around I was asking for trouble.