OK...seems like many are asking with no response from OP so let me throw this in here...according to the website, these wheels were 18x8.5 and 18x10.
Both having a 25mm offset.
So, front.....take 8.5 and add 1 inch. now take 9.5 and divide by 2. now take 4.75 and add the offset of 25mm which converts to about 1 inch and POOF!!
Front is 5.75 backspacing.
Lets plug the numbers into the rears
rear.... take 10 and add 1. now take 11 and divide by 2..now take 5.5 and add the offser of 25mm or 1 inch and again.
Rear is 6.5 backspacing
As far as tires go, a good fitting tire for the front would be a 245/45/18...the rears would fit a 275/40/18 nicely. Both would be the same exact height.
As for the build, I dont love it and I dont hate it. I agree that you can choose to customize your car any way you like. I mean some could say that anyone who has changed anything on their car such as turbo, ic, wheels, injectors, paint, gauges, radio, etc is taking away from what the car is.
At the same time, I would never use anything other than a Buick V6 in a Turbo Regal...but thats just me. Nonetheless, definetily a great effort....Good job!