Corvette Wheels and Tires - C5 Retirement Party

So, I went for 18x9.5-inch wheels up front and 18x10.5ers out back. HRE's ads show six designs in the 540 series; they offer three others on their Web site. I opted for one of "the others," the rather Teutonic looking, 15-spoke model 549. And instead of the usual polished finish, I thought HRE's charcoal paint option for the centers would really compliment the coupe's light pewter metallic paint. A large proportion of Corvette Wheel Specialists' business is chrome-plated wheels. Mike Sweeney suggested that I have the outer rims chromed rather than polished, both for the slight extra flash factor and because I could pretty much forget about having to polish the rims on a regular basis. It was an excellent suggestion, one that I heeded.

Now it was time for tires. I took the same approach as with the wheels; stick close to Z06 sizing and I am fairly certain there'd be very minimal chance of clearance issues. The rear was a no-brainer-Z06 size tires (295/35ZR18) were the only choice as far as I was concerned. The front skins would take a little figuring since I was using 18-inch rims. I wanted to keep as close as possible to the OEM tires' overall diameters, both front and rear, to avoid potentially throwing off the ABS and to keep from severely impacting the speedometer calibration. Front tires on a Z06 are 265/40ZR17s. The 265 refers to the cross section (overall width) of the tire, measured in millimeters; 40 is the aspect ratio of the tire, which means, in this instance, that the sidewall of the tire is 40 percent of its width (approximately 106 millimeters); Z is the speed rating; R indicates a radial ply tire; and 17 is the wheel diameter. If I step up the front wheel diameter from 17 to 18 inches and don't compensate for the 1-inch increase in wheel diameter with a reduction in the sidewall height or aspect ratio of the tire, I'd end up with a much taller front tire and wheel package. Not good, SUV size tires and wheels would look absurd on a Corvette!

The natural step is to reduce the aspect ratio; in this instance, to go from a 265/40ZR17 to a 265/35ZR18. Plus sizing is the common term for increasing wheel diameter, and the general rule is that for each 1 inch of wheel diameter increase, you add 10 millimeters to the tire cross section (width) and move one step shorter on the aspect ratio (the height of the tire sidewall). Going plus one on a Z06 front wheel and tire would then yield a 275/35ZR18. So, I decided to see how these changes would compare to the standard C5 tire/wheel packages. All of the following dimensions, except for the tire sizes, are in inches, and all dimensions were taken from Yokohama Tire Corporation's 2003 high-performance tire application booklet.

After looking over the numbers and checking with a few tuners and tire/wheel experts, I went for the 275s up front. Next would be to select a manufacturer. One of the quickest ways to find who offers what, tire-wise, is to conduct a search for the desired sizes on the Tire Rack's excellent Web site (www.tirerack.com). I found three tire manufacturers (Kumho's ECSTA MX, Michelin's Pilot Sport, and Yokohama's AVS Sport) that offer the exact combo I was after, and one (BFGoodrich's G-Force T/A KD) that offered the 295/35-18 rears, but with a 265/35-18 front. Goodyear, the OEM tire supplier for all C5s ("standard" and Z06) doesn't offer a Z06-size, 18-inch front tire in the superb Eagle F1 Supercar line, and while they have standard C5-size (and sizes for the ZR-1) in their new Eagle F1 GS-D3 ultra-performance line, there is no Z06-size tire in that product line.

I opted for the "Yokes." Why a Japanese tire on America's sports car? Goodyear, the only American manufacturer, doesn't offer the sizes I needed. BFGoodrich was close (but no cigar) for my ideal sizes and is no longer an American-owned company. Michelin, which owns BFG, makes excellent tires, but we were fitting Pilot Sports on another C5 at nearly the same time. Kumho probably makes excellent tires, but I have no experience with them and don't personally know anyone who has. I do have nearly two decades of very satisfactory experience with quite a number of Yokohama's ultra-performance tires on quite an array of automobiles ranging from a gray-market Alpina BMW to '80s and '90s vintage Mustangs, and on an extremely rare '99 1LE Firebird. I called Yokohama and ordered a set from Mark Richter, Yoke's resident HiPo tire guru and owner of an extensively tweaked C5 Hardtop that's seen more open track miles than most of us could even imagine.