Volvo steering issues V40 2016

[magic-torch]

I recently bought a 2016 V40, I test drove 2, both had the same engine but the trims and extras where different. I bought the one with bling, 19inch wheels. The other one drove lovely and had 17inch wheels I think, but the one I actually bought drove differently on the test drive. It was the exact same test route but the steering pulled me all over the road.
I mentioned this and the sales person said it might be the tyre pressures or tracking and they would be sorted before I picked it up.

Stupidly I believed them blindly and picked it up and said no more. Unfortunately it's something I'm now struggling to live with, some roads are worse than others but it is always there, and in the wet, well it's dangerous. If I get on a white line whilst overtaking a parked car it can pull me into the parked car.

I've checked tyre pressures myself and they are fine. I will be asking the dealer to do a 4 wheel track in a couple of weeks when it goes in, but is there anything else I need to be aware of that could be causing this, or is it the size of the wheels, which is all I can see as being the difference in the 2 cars I test drove?