So that you use up the tyres evenly.

Remember, power and steering goes to the front wheels.

I think what is being implied here is that, it does not matter when you purchased your car. January 2010 or December 2010. Both will have the tag "2010" on your car when it comes to selling it in the future, hence it's better to get a Jan 2010 and use it for almost 12 months, and yet it'll sell as well as a December 2010 car, with all other variables being equal.