Hi I have a Kia Rio (diesel 1500) 56 model, I've just noticed that one of
the tyres is wearing on the outside edge, if this hard been on both front
tyres I'd have suspected the tracking. Just wondering if anybody has any
ideas what the cause could be?

It started about a month ago.  I filled up with gas at Costco.  I
drove home and the car sat overnight.  The next day, when I tried to
cross the street, the car could barely move.  And the check engine
light went on.  I assumed water in the gas.  I treated it with water