The 275/35/20 fits the front of the car perfect. I won't NOT go wider than that on a 10" wide rim.
Between the wheel and the shock body I have about 1/2 - 3/4", just enough to slide a finger between them, which is kinda my minimum clearance for wheels / tires / other components.
Here is the test fit on the wheels.....20x10's, 40mm offset, 7.0" backspacing...they fit, but I would not be comfortable even a hair wider....
Out back you're good. This is the same rim and there is plenty of room. I'd have no issue putting an 11" wide rim and a 305 or 315 back there...
And, all mounted up with 275/35/20's all the way around....