I just bought C5 chrome rims and want to know if i put the275/40/17 on them do I have to change anything on the Z. And also will the speedometer have to be recailbrated? Thanks

 

The 275/40-17 has the same outside diameter as the stock (if your car came with the Z-rated tire option) 245/50-16's, so no recalibration of the speedo is necessary. If you had a different "stock" tire than the 245/50-16, a minor recalibration might be required.

When fitting "C5" wheels:

- What is the width of the rim and the offset? This will determine whether the wheel fits properly in the fender, and whether the tire rubs on anything. "C5" wheels come in a variety of widths and offsets, depending on the years. Most of the 17's have a 54 to 56mm offset, which is a good match for the 4th Gen F-Body. Shouldn't rub on anything.

- Some of the very early 4th Gens have a larger diameter hub on the rear axle than on the front hub. Putting newer wheels on older 4th Gens can sometimes require a light sanding of the inner diameter of the hole in the wheel, to provide the required clearance. That should not be a problem on you 97, since they appear to have corrected the axle hub diameter problem sometime in late 96 or early 97.

 

Thanks. Yeah it came with the z rated tires. 275/40/17 will fit in 17"/8.5 correct?

 

The only manufacturer I know of that recommends putting their 275/40 on a 17x8.5" wheel is Dunlop. Most others recommend a 9" minimum wheel width.