Admittedly, it's far from a statistically valid survey, but if I were to judge by the letters and e-mails that come into VETTE Command Central, and the comments and questions I hear at various Corvette events around the country, there are a lot of C5 owners who find the factory-installed Goodyear Eagle EMTs to be, well, less than the greatest. Hey, it's no big deal to switch over to some other brand when the OEM run-flats are due for replacement, right? Only it is a big deal, and a wee bit more complex than that.
Actually, there are a couple of complications. First is the fact that the C5 was engineered specifically to use a run-flat or extended mobility tire, and there is no provision in the C5 Corvette for a spare tire. Obviously, that's a potential problem, especially if you take that C5 for a long trip. The second problem has to do with the sizes of the tires (and wheels) that The General fits on each and every C5. The front tire is a 245/45ZR-17, a very common size and one that nearly every tire manufacturer offers in at least one of their ultra-high-performance tire lines. The rear tires, size 275/40ZR-18, are real oddballs. That specific size is, as far as I have been able to determine, unique to the C5, with no other OEM applications.
It takes a major (well into the six-figure range) investment for a tire manufacturer to engineer and tool-up molds for a specific tire size, and there has to be the potential for substantial aftermarket sales to justify the up-front investment. It's different for the OE (Original Equipment) supplier. In the C5's case, Goodyear is contracted to construct and supply a given quantity of tires over a specified time period directly to GM's Bowling Green plant, and every C5 rolls off the line on the same spec tires. Unfortunately, there is no impetus for Goodyear to improve on the product, at least as long as Chevrolet is satisfied with the tires.
That doesn't mean there is anything wrong with the OE Goodyear run-flats. But, it also doesn't mean that all of the 74,000-plus buyers of '97-99 C5s are necessarily ecstatic with the performance characteristics and wear of them. And, until recently, there haven't been many alternatives for C5 owners who choose to retain the stock tire and wheel sizes, and either want to upgrade their rolling stock or need to replace worn tires.
But, by the time the 2000 model run has ended, there will have been over 100,000 C5s built and sold. Over 100,000 cars equals over 400,000 tires, and that's a sizable enough market for replacements to get the marketing mavens in many tire manufacturers salivating-particularly when you're talking about high-end, ultra-high-performance specialty tires.
One of the first tire manufacturers to take advantage of this potential opportunity is one of America's oldest tire manufacturers, Firestone, now a part of the Bridgestone corporate empire. Firestone's original Firehawk SZ50 series of ultra-performance tires, which was introduced in 1996, has been justifiably regarded as one of the best tires of its type. This last February, Firestone introduced a second generation of this tire line, called the SZ50 EP (for Extended Performance) at a series of special test sessions for select media and Firestone dealers, held at Firebird Raceway in Chandler (suburban Phoenix), Arizona.
So what's any of that have to do with C5s? A lot! In addition to the usual array of sizes (including ones to fit any C4 except the rear of a ZR-1), Firestone also debuted two new sizes in the SZ50 lineup, with what they're calling "Run Flat Technology"-specifically for C5 Corvettes. That's right, 245/45-17s and 275/40-18s, the correct factory sizes. And just to make things a little more interesting, they had six new 2000 Chevy Corvette convertibles, shod with the new 'Stones, on hand for us to test-on track.
Actually, Firestone was debuting four new tire lines; the aforementioned SZ50 EPs and C5-specific SZ50 EP RFTs, and a couple of new product lines for passenger cars and minivans. There were different diving exercises, at different sites on the Firebird facility, and different types of vehicles to be tested for each new tire. All driving exercises were done with and under the supervision of professional high performance driving instructors. I'm not into minivans or six-cylinder Mustangs, and don't even own a car that would use "everyday" type tires. Evaluating all four new tire lines was part of the program; I did it, the new tires for sedans and minivans are exemplary for their intended purposes and markets, and I'll let it go at that.