Your having a problem because these wheels are not made for this car. If this was GN offset and sizes they would of sold the first day at asking price. I suggust you find out what they were built for then list on thAt forum.
I love them and would possibly be interested but the sizes just doesn't seem correct for the TTA without sticking out of the fenders and or rubbing on the inside. "TTAFAN" just put new Weld Magnum's on his TTA and they appear to be maxed out at 9" wide with a 5" BS and a 11.5" tire...the 315's are 12.4" wide. I have seen the car in person and can't imagine another 1.75" on the outside and 0.75" on the inside...his car currently has about 0.50" clearance both inside and out. If your measurements are correct the rears would stick out past the fender 1.25" and would rub on the inside. If the wheel is a 11.5' w/5.75" BS that is a 50/50 offset more commonly used on older Corvettes. The fronts you have listed would fit the back of a TTA perfect but would probably rub some mounted up front on the inside since the BS at 5.312 is where the stock BS is only 4.750. It may be real close since some guys have put rear TTA wheels up front with some success.
If the tires are junk you should remove them and get exact measurements of the wheels. Plus junk tires will just add to the shipping weight/cost for no good reason.
our local tire shop has a gauge that seemingly comes with the tire balancer since it hangs on the machine and they need to measure the wheel before they balance it. they measure the rim with the tire on it. maybe you could bring it to a larger volume tire shop and they could measure them for you without the hassle of removing the tires. a mom and pop shop may not have modern equiptment.