What sort of alloy wheels are they? In other words, does the wheel fit snugly over the spigot to centre the wheel correctly? If they are after market alloy wheels, do you have the correct spigot rings? Just my 2p into the jar.
On these engines, there is a twin (Gemini) chain which runs between the crankshaft and the injector pump. The cam belt, in turn, runs from a pulley on the injector pump up to the camshaft. Changing the cam belt does not require the chain to be touched at all. Its a bit of a mystery as to how the chain could have been affected in such a way.