Is it possible to lower with these wheels and tires?

I have a 2004 Tahoe with wheels from a newer Tahoe on it that are a bit wider than what came on it.

I am wanting to lower the back two inches but I may end up doing a 1/3 drop on it, just not sure yet. But I noticed the other day just kind of randomly that my tires are already slightly rubbing the inner fender on the back.

I'm hoping that someone else has a setup like this and can give me some advice if I just need to do a little trimming to the inner fender or if I will have to do something a little more drastic like wheel spacers?

Here are some pics, the arrows are drawn to the area that the tires are rubbing.

The tires are 275/55/R20 by the way.

i had a buddy when i went to UTI had a 2500 duramax 4x4 and bought a new set of rims and tires that were a little to wide and rubbed and he just trimmed his **** up with a dremel tool and problem solved you couldnt even tell were he trimmed his **** up at

also my ass end sits up like that a little and i was gonna do the same thing but i found out my front shocks are shot i was told when put new shocks on it would sit level
does yer tahoe bounce and sway in the front you mite have the same problem if yer shocks are good then you can turn the torsion bars up in the front to level it out just make sure its on a lift when you crank them up then set it down and measure your ride hieght i recomend keeping your ride height a half inch lower then what it is in the back

My shocks and struts are fine. I will go ahead and replace them while I am lowering it though. I don't want to lift the front of it, the most off roading this thing does is popping a curb in a parking lot on occasion because I'm too lazy to drive around it.

After looking at this a little closer with a few buddies of mine I think just cutting that plastic away and turning around the upper bolt that holds the shock will be fine. It'll be close but should work okay, even if I decide to go with the 1/3 drop.