Have a similair problem on my Accord. It has the 17" option with a 225 tyre. Wider tyres have a habit of picking up the grain of the tarmac, ie when one side has a better grip level than the other then this affects roling resistance which can effectively 'pull' the car accross the road. It is more pronounced on wider tyres which is the trend for newer cars.
That's also why it can be affected by tyre pressure which also affect roling resistance, slight differences accross axel can pull the car too.
Solution - keep your pressures even and keep 2 hands in the wheel
