Tires: Gas mileage, gas mileage, season tire

Question
I've just visited three stores and asked each to make tire recommendations for the tires which will provide the best mileage for my 2001 Toyota Sienna. It appears that they just gave me quotes on the tires they had in stock. I was wanting an explanation of tire pressure, tread pattern and wall stiffness (etc). What criteria should I use to make my tire selection (this is not necessarily a brand question)?

Answer
Tim,

 I would look into a touring, a/s season tire.  As for wall thickness you or the dealer should match the load index and speed rating of the OE tires, this info along with the recommended air pressures can be found on the tire placard located inside the driver's door frame.

Brett