Imagine the size of the car! No seriously, I think these tyres are the kind used on those hugely-oversized mining vehicles (see more here).
These mammoth tyres act as a buffer between docking (or moored) boats and the harbour wall. My car's tyres cost between R800 and R1200 depending on the brand, with some luxury 4x4's tyres costing 4 or 5 times that price. I wonder what these tyres would cost and hope that the harbour sources used tyres from mining companies instead of buying them new - it's a great way of recycling rubber!