Looks great, more filling....
Looks great, more filling. Besides the appearance improvements, the 295-size non-runflat rears provide tons of grip.
But if you want to keep the runflats, Yokohama's AVS Sport EMTs are a good choice. The C5-sized rubber features the same basic tread pattern as the "regular" AVS Sports, so grip is good. Sweeney and I agreed that, at least in our informal testing, that the Yokohamas ran quieter than the Goodyears the '99 was wearing, and also had better "feel" (meaning they seemed to have a bit more sidewall flex). Along with the AVS Sport tread pattern, we'd have to say that the Yokohamas are an attractive alternative to the OEM Goodyears.
Easy To Fit
As we said earlier, this article is based on OEM and OEM-style repro Corvette wheels. Since we're dealing with a known quantity, the only measurement we'll deal with here is offset. In short, the offset of a wheel is the distance from its hub mounting surface to the centerline of the wheel. As you can see in the chart, the offset found on the repro wheels is very close, if not identical to, what came on the factory wheels. Where it varies, CWS' Mike Sweeney assures us that the difference is too small to matter. The 2mm difference found on two of the 17x8.5-inch wheels, for instance, only amounts to about 1/16-inch, which won't really affect the wheel fitment.
Looking up and in from under...
Looking up and in from under the car, we can see that the 18x10.5-inch wheels and 295/35ZR18 rubber clears without a problem.
If you decide to go with wheels that are wider than the stock C5 or Z06 units, you'll also need to deal with backspacing. Backspacing is the distance from the back edge of the wheel to the hub mounting surface, and can be easily measured with a straightedge and a ruler or tape measure. The backspacing on our '99 guinea pig's rear wheel, for instance, is 7 3/4 inches. Again, make sure you get professional help if your motto is "Wider is Better" (sorry, Pontiac).
This chart contains the basic info you'll need to interchange OEM rims or to fit factory style repros. The blank spaces are blank, of course, because GM didn't make the rim size listed. For instance, The General never made an 18x9.5-inch, Z06-style rim. Luckily for us, the aftermarket has stepped in to fill the void, opening up a world of possibilities.

Just out of curiosity, we...

Just out of curiosity, we then paired a 265/35ZR18 with the 295/35ZR18 rears. The 18-inch fronts are just a hair less than half-an-inch shorter (25.3 versus 25.7) than the both the 275/40ZR17s and the 245/40ZR18s.

Yokohama doesn't make a 265/40ZR17...

Yokohama doesn't make a 265/40ZR17 front tire (stock Z06 size). They do, however, make a 275/40ZR17, which fits perfectly and provides a nice, fat contact patch.

Before finishing up for the...

Before finishing up for the day, Sweeney rolled out one more setup for us to look at: '01-style wheels in Z06 sizes (17x9.5 front, 18x10.5 rear) and all dressed up with our Z06-sized Yokohamas. No problems with the fit, and it looks great!

Want the Z06 look, but with...

Want the Z06 look, but with stock runflat tires? That's easy. These Z06-style chromed wheels are C5 sized: 17x8.5 front, 18x9.5 rear.