NO, YOU SHOULD NOT HAVE THE SAME TIRE. YOU SHOULD HAVE WHATEVER TIRE WAS EQUIPPED FROM THE FACTORY.
The tire is an important part of the performance of the car, and if ford decided that the performance and value of the car would best be delivered in factory configuration with 135/7R16 tires from the factory, then that is how you test the car. What you are saying is stupid. You are upgrading parts from the factory to be more up to par with what another car had from stock.
If I am going to compare a 240sx and a Corvette in straight line speed, I am not going to drop an LSx into the 240sx to make it fair. Are you that dumb in real life, or do you just pretend?
Stock vs. stock means just that.