I don't think a lot of Avalons here have used 19s; most 18s or 20s X 8.5 width. I have 20 x 8.5 on 245 35 20s and they rub on the drivers front mudflap at a 1/4 turn(so far only if backing out the driveway with the wheel turned to the left when I hit the curb getting on the street). The wheels have an offset of 42MM and sit almost flush.
Unfortunately, there are no cut and dry answers of what will rub/not rub as different brands of tires are different heights on different wheels/widths.
I believe the camry crowd that run the wider rims are running super low profile tires and stretching the tires and that is not the look I was after(this leaves the rim very exposed to damage rendering any rim protector on the tires usless). Also I believe they are relief cutting the fenders edge, folding them up and also pulling the fenders out a little to stuff these; some guys are on drop springs as well.
I would look at the website of the brand of tires you are planning to use and see how tall they are compared to others and try not going higher any over stock 215 55 17 = 26.3" if you are planning on going that wide with that offset, the General Exclaim UHPs I have are 26.8" which comes up to 1/8" taller overall. These measurements are unmounted, so again, hard to say what will/not fit without someone chiming in who actually has the same wheels to say what tires won't rub.