Sorry to go off topic slightly but this reminds of few years ago I went to a breakers to strip some bits off an Elise. After getting what I was after I looked at the wheels (possible purchase?) and realised the reason it had gone backwards through a wall was because the rears had been fitted down the near side and the front wheels down the offside. So, 16 inch wide wheels down one side, 15 inch skinny' down the other. No wonder they crashed. It's not like it's an easy mistake to make either.
Back on topic tho, yeah, mismatched and or cheap tyres make me cringe in adverts, if someone skimps on the few cm2 of rubber attaching them to the road, what else have they short cut you can't see.