i will save you the time and frustration, i did that same minitub gained a whole( 1 in) in the center and none where it counts !
i am currently putting the car back to stock so i can run a rear seat and do the same very thing with out the a body dart mini tub .
why destroy your car ? i run a 15X10 rim with 28 x 13.5 tire tucked without a problem. hope you dont cut up that awsome car
FOR NOTHING . THE OFFSET ON MY RIM FOR A 15X10 IS 6in