Many thanks Zip. When I bought the car a few months back and drove it home (approx 140km) I did not notice any vagueness in the steering. A few days later when I checked the tire pressures, they were up around 45psi. I figured that the previous owner had simply let the garage attendant check the tire pressures (very common here in SA), hence the over-pressure. I deflated them to the recommended pressure which resulted in a smoother ride but some vagueness in the steering. That's when I also spotted the incorrect tire size on the front. Perhaps the previous owner had deliberately over-inflated them to give more precise steering?