What volcanic rock does to tyres

After driving some 2,500 km –mostly across travel and rock roads– today we had our first puncture, or perhaps I should say our first shredded tyre. Volcanic rock is not kind to car tyres, and the road today was littered with abandoned rubber tyres. This one clearly has no future and we shall have to dig deep into our pockets to replace it. I think our decision to carry two spare tyres was a sound one.