Since its introduction last fall, the new Z06 has proved to be quite a hit with both the motoring press and Corvette buyers everywhere. Those of us fortunate to have driven one can confirm that all the fuss is warranted.
While the 505hp LS7 engine has generated the most headlines, one of the '06 car's biggest advancements is its imposing new wheel-and-tire package. Extending a longstanding trend, Goodyear was again selected to be the original-equipment tire supplier. The company responded with a completely redesigned Eagle F1 Supercar EMT (Extended Mobility Tire), sized 275/35R18 in the front (MSRP: $400.88 each) and 325/30R19 in the rear (MSRP: $481.70 each).
Team VETTE has spent a lot of time watching standard C6s being dismantled. As described elsewhere in this issue, we had a chance recently to see Callaway Competition do the same thing to a new Z06. In every case we were amazed at how similar the underpinnings of the C6 platform are to those of the C5.
It wasn't long before we began wondering if the Z06 wheel/tire combo would work on our "Pewter Rocket" fixed-roof coupe. To find out, we called Goodyear and spoke with tire engineer Mike Skurich. Mike was optimistic about our using this setup on our C5. He told us that although these tires were developed for the C6, their performance in an earlier application should be very similar.
Mike also agreed to give us some background on the development of this tire. He began working closely with Mike Neal's Z06 Corvette Chassis Development team in 2001, and he also worked with Corvette Chief Engineer Dave Hill's engineering team.
Goodyear learned much from its original EMT tire, which was standard equipment on the '97 C5. Specifically, engineers learned how to reduce tire noise and improve ride. The new tire's mold geometry and profile had a huge impact on improving performance. This version has less material, which reduces heat, sidewall thickness, and weight. It also has an asymmetric mold shape that really helps performance, and its tread depth was reduced from 101/432 to 81/432, resulting in less tire heat. Rim-flange protectors not only grip the wheel rim when the tire is deflated, but also enhance sidewall stiffness for improved handling.
Although GM reduced the run-flat criteria (that is, how long you can drive at 55 mph on a deflated tire before making repairs) for the new tire from 200 to 100 miles, the repair criteria remain the same: If a puncture occurs in the center crown area, it can be repaired. If the puncture occurs on the outer edges of the tire, the tire must be replaced.
The new Eagle F1 features a six-rib design, as opposed to the five-rib design found on the older version. This provides a uniform void for water dispersion and more-even tire-pressure distribution. Even tire pressure helps footprint contact with the ground. Mike finished our discussion by telling us that the best suspension setting for these tires is -1.0 degree camber front and rear and 30-psi tire pressure front and rear, as recommended by Chevrolet. We thanked Mike for his time, and he arranged to have Goodyear send us a set of these new tires for our project.
Our next challenge was to find suitable wheels for our new tires. While working with Callaway on another project, we learned that stock '06 Z06 wheels aren't a precise fit for a C5. When mounted, they protrude too far out of the fenderwells for our taste. We liked the factory look, though, so we contacted Mid America Motorworks for recommendations. Mid America suggested Factory Reproduction versions of the '06 Z06 wheels that bolt on to our C5. Factory Reproduction wheels are made from 356 aluminum alloy and use the counter-pressure casting method for maximum strength. Each casting is CNC-machine finished, pressure tested, and inspected for lateral runout. Mid America suggested we use 18x9.5-inch fronts with a 57mm offset (PN 624-023) and 19x11-inch rears with a 64mm offset (PN 624-025). The front and rear wheels are sold in pairs and retail for $699.99 per pair.
Once our wheels and tires arrived, all we needed was a facility capable of properly installing them. Fortunately, Maher Chevrolet, in nearby St. Petersburg, Florida, has an excellent reputation for Corvette service. Longtime Service Manager Bill Palicka even owns a black '02 Z06 and a fully restored '57 roadster. Bill agreed to let us document the installation process at the dealership's full-service center.
Bill assigned Assistant Service Manager John Wysocki and Service Technician James Ritchey to our project. James first removed the '00 wheel sensors from our existing rims. John explained that there are two types of C5 tire sensors: one for the '97-'00 C5s and another for the '01-'04s. It's important to use the correct sensor type, or the sensors will not work properly. John also told us the earlier sensors require a tire-sensor grommet (GM PN 25754190; $3.42 each) if you install them on C6 wheels. This ensures proper rim seal.
Once we had the correct parts, James installed the sensors and mounted our new Goodyear tires. He then water-tested each one for leaks. Each wheel was carefully balanced using adhesive weights for maximum accuracy. Finally, we installed four chrome Z06 wheel caps (GM PN 9597006; $31.51 each), which look great on the factory reproduction wheels.
Even though the 11-inch rear rims are designed for 295/30 tires, we wanted to install the larger 325/30s used on the new Z06. This reduced wheelwell clearance, though not to the point that any interference was evident. Still, we plan to check our rear wheels occasionally to make sure they aren't rubbing.
After the alignment was completed, we were ready for a testdrive. We immediately noticed how quiet the new Eagle F1 tires were on the road. We experienced no tire vibration, even at higher speeds. The tires handle great in wet conditions, and dry-pavement cornering grip is simply stupendous. And although this wasn't intended to be a cosmetic upgrade, we do enjoy the looks the car gets with its new "blinged" wheels and meaty Eagle F1s. If you want to upgrade your C5 with the '06 Z06 wheel-and-tire combo, contact Goodyear and Mid America Motorworks. You won't be disappointed.