I am looking at purchasing a set of TTII 16x8 for my 2000 camaro z28. Does anyone know what backspacing I need, that will best fit my car without making any mods?

 

The stock wheels on your car were 16x8" with a 55mm offset. You can reduce the offset slightly, if you want to move the wheels toward the outside of the fender a bit. I would guess you could go as low as +38mm. Depends whether you want them to sit in the fenders like the stock wheels, or move a little bit toward tha outside of the fenders.

Just curious.... why did you choose to replace the stock wheels with something the same size? Many people go up to the 17" wheels, picking the 17x9" 50mm offset used on the SS and WS6 models, or 17x9.5" with an offset in the range of 45-56mm. You get a bit better selection of tire sizes with the 17" wheels. With the 16" wheels, you won't find a true "high performance" tire any larger than 255/50-16.

 

The tires I have are practically brand new, with
only 2500 miles on them. I could trade these in for
some 17's but, I have not really decided.

If I do go with the 17x9.5 TTII's the spacing would be the
same, correct?

 

Check the "FAQ" stickied at the top of the Wheels and Tires forum topic listing. It has photo links to cars with 17x9.5" wide wheels, ranging from 38mm to 56mm.