Sub frame alignment?

[jlwdvm]

If your wheel base is the same on each side, wouldn't the rear end have to be square with the front subframe (since the wheels are attached to it)? The 4 corners made up of the tire patches would be square...right? I have the sub centered side-to-side according the the pinch welds. Currently I have the wheel base within an 1/8" when comparing drivers side to passenger. I am using wheel studs on the rear with the car at ride height and a level placed on 2 studs and then measuring to a stud on the front rotor after doing the same and also making sure the rotor is the same distance from the frame so toe isn't a factor.