Go over to
www.svtperformance.com and search for "IRS bolt" to find all the discussions about clearance between a bolt on the independant rear suspension and the wheel. The bolt doesn't hit wide wheels or tires when your sitting still, but it's possible when the wheel moves through the range of motion allowed by the suspension. Some folks found a suitable hard bolt with a smaller head and replaced it when getting larger wheels in the rear.
I'm running 275/35ZR/18 tires on the stock 18"x9.5" rims on my 2000 because that's as large as I can go and still rotate tires front to back to try and even up tread wear. Plenty of guys on the forum have gone larger in the rear and posted their combinations.
Ed