https://www.toyco.co.nz/toys/siku-3734-bus-man-lion-city-4006874037346

One of my boys has the above toy bus but sadly lost one of the tyres today. Try as I might I can't find anywhere online to buy spare parts - most places will take me to a site where I can buy the whole thing, but I only want a spare tyre. Does anyone know if Siku even do spares? I know Lego has a pretty good spare parts service, but I can't find anything for Siku.

Sorry if this is the wrong place in the forum, please feel free to move if required.

Thanks :)