Wow two turned into four REAL quick

, lots of questions at once. You won't need to change anything to fit those tires/wheels on your car. You might notice some rubbing at extreme ends of the steering, and if you choose to, you could use a steering stop, but I just back off if I hear them rub. I have 235/50/18's on my 4.0 in front, and 275/45/18's in back. The brakes will be fine. The only prob is if you go bigger brakes on a smaller wheel. As far as I know, you can use the stock size rear brakes on the 8.8 axle, at least I hope so, cuz I just bought an axle and have NO more money for brakes!!

I haven't heard anyone say that you have to buy bigger brakes, although, I want to in the future.
Don't really know if not using the tps will do anything... but my guess is no. You just won't have that info anymore, bfd, we have been driving for 100 years by just looking at our tires to see if they were inflated before we drove, and we did just fine.
As far as your 17/8's working on an 8.8??? That is what they come with stock a GT soooo YUP.. they'l work just fine.
Again as I mentioned before, I have 18/8's and they fit like a bug in a rug, and I didn't have to change a thing. Just bolted em on. Your tire will be just a smidge wider in front than mine, but there is gobbs of space and it will all be just peachy.
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2005 Torch red, predator 93 octane, K&N filter, Pypes true duals, Eibach Pro-kit springs,4.10 posi 8.8 rear end. GT fanblades with Eagle F1's, GT500 rear bumper/spoiler/front splitter