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New NON-RUNFLAT ultra-performance Goodyear for C5s

Hib Halverson

Technical Writer for Internet & Print Media
Jan 10, 2001
CenCoast CA
71 04 12 19
Action Center members:

Goodyear has just scored a virtual "one-two punch" in the ultra-performance tire market.

A couple of months ago, it introduced the Eagle F1 Supercar (OE tire on 01-03 Z06es) in replacement sizes to fit non-Z06, C5s.

On Sept. 17, Goodyear took its second swipe at the ultra-performance market by introducing the "Eagle F1 GS-D3" (or just the "F1" as Goodyear abbreviates it) to the North American market. The F1 GS-D3 fills out the aggressive, performance end of Goodyear’s tire line by replacing the F1 GS for all non-EMT/non-run-flat applications. Currently, it is available in only non-Z06 C5 sizes but that may change eventually.

This new tire is an improvement over the F1 GS EMT in dry traction and noise and ride. By virtue of a completely different tread design, the tire is a heck of a lot better in the wet than the F1 GS EMT, too.

Where does the F1 GS-D3 sit in relation to the F1 Supercar? Well, the Supercar is still Goodyear's most aggressive, dry traction tire and remains one of the top choices if you want a DOT-legal tire for hard-core performance driving on the street and occasional trips to the track.

The GS-D3 fits in Goodyear's C5 ultra-performance, replacement tire line just a small step below the Supercar. It doesn't have quite the limited tread depth and lunatic-fringe dry traction, but it's better in the wet and is quieter. My guess is it might also be just a bit better in tread life, too.

Goodyear Marketing Manager for Auto Tires, Bob Toth told me last week, at a media program Goodyear hosted to introduce the new tire, that all 39 sizes in the GS-D3 line should be in the retail pipeline by late October. The C5 sizes of this tire are made, alongside the F1 Supercar, at Goodyear's plant in Lawton, Oklahoma.

If you’re read this far, you might be wondering about running a non-EMT tire on your C5 which has no spare. The solution is the “Tire Inflation Kit” GM includes with every Z06 and any Corvette exported to a market where run-flat tires are not legal, such as Japan. The Inflation Kit includes an aerosol can of sealant and a 12-volt air compressor. You inject the sealant into the flat tire with the aerosol can then reinflate the tire witht he compressor. This kit will fix any small leak such as what you’d get from a nail, a piece of glass or other common road hazard. While the Inflation Kit was designed by GM and works very well for most typical leaks, it will not solve problems with significant tire damage such as the large holes EMTs can sustain and still be driven limited distances. There is also another difficulty with the Inflation Kit and that is, after its used to fix a leak, the Low Tire Pressure Warning System sensor on that wheel will usually be damaged by contamination with the sealant. Unfortunately, these are compromises you must accept if you want the better tire performance available with a non-EMT tire.

On Sept. 18, I spent a day and half testing this new tire at Goodyear's Proving Ground in San Angelo, Texas. A good part of this 7250-acre installation was turned over to two groups of we media folks for two days of tests and briefings. Oh, yeah, we did a little “playing” too. Writers were treated to rides in Goodyear’s newest airship, the recently Christened “Spirit of America” along, with a Texas-style BBQ complete with steak, potatoes, Lone Star Beer and even, a pet Armadillo named, appropriately, “Tex” (runing loose) and Rattlesnakes (in glass cages).

The San Angelo’s facility's vehicle dynamics area, a 540,000 sq/ft. asphalt pad (for comparison a football field is only 90,000 sq/ft.) with a 1-deg. slope and a water distribution system that spreads a layer of water, .050-.060-in. thick over the entire facility, was the site of some wet handling tests I ran. Goodyear had turned on the water and set up a braking test and a low-speed autocross. My test cars were three C5 Convertibles with automatics and base suspensions. One had a set of Michelin Pilot Sports. A second had a set of Bridgestone Potenza S-03 Pole Positions and the third car had F1 GS-D3s. Tire sizes on all cars were stock. Tire pressures were 30 psi cold.

The braking test procedure was: accelerate to 55 mph then, upon passing a set of start cones, apply full, ABS braking. From the start cones, there were measurement signs every ten feet. The Pilot and the Potenza brought the car to a stop in 87-90 feet. The new Goodyear's performance in the same test was 83-85 feet for an approximate, 5% improvement.

The autocross was not timed and was used as a subjective evaluation of the car's limit handling on a wet surface. After driving all three tires, I felt the Goodyear had a slightly higher breakaway limit in the wet than both the Pilot Sport and the S-03 Pole Position. Also, compared to the Goodyear and the Michelin. the Bridgestone didn’t seem as predictible. Once it began to slip, it broke-away abruptly. With the other two, once I felt initial breakaway, things happened just a bit slower. I observed two different drivers spin the Bridgestone-shod car in the same spot on the course. It was a place where an unprepared driver was liable to lift abruptly in a turn. Once the Bridgestone hits its limit in the wet, it breaks-loose instantly. Not a good thing, in my opinion.

Later, Goodyear supplied objective, traction coefficient vs. percentage of slip data for all three tires. It was taken at 60 mph in the wet. While at that higher speed, each tires' hydroplane characteristics may have had a slightly greater effect, the data seemed to confirm what I'd felt in the 40-50-mph slalom. This data showed that the new Goodyear is a moderate improvment over the Michelin and slightly better than the Bridgestone, until the slip angle reaches 30-deg. Past that (angles you'd almost never see unless you were loosing or had lost control of the vehicle) the Bridgestone and the Goodyear are about the same with both having an edge over the Michelin. This testing convinced me that, right now, the best choice in an ultra-performance tire for a Corvette (or any performance car, for that matter) that might get driven in the rain is a Goodyear Eagle F1 GS-D3.

I asked Goodyear Engineer, Melissa Montisano, what features of this new tire would cause it to better both those other, admittedly good tire brands in the testing I did. She told me that in the 55-mph. braking test and low-speed autocross, on surfaces wetted to a depth of .050-.060-in., the tires' hydroplaning characteristics are not the most critical factor. What makes the F1 stick better in the wet at those speeds is its tread design, its tread compound and the size of its footprint.

That afternoon, I moved to the Proving Grounds' 2.5 mile road race course for a subjective evaluation of the F1 in an at-limit, dry traction environment. The test car was an Audi A4 sedan with a 220hp V6 and a six-speed manual trans...not really a car I'd choose to use for a tire test, but one that is on the "sedate" end of the target market for this tire. Again, the tire sizes were stock and the tire pressures were 30-psi cold.

I ended up being quick time of the day amongst all other media present so, even though I'd never driven that track and never driven an all-wheel drive car, I knew I'd run the new Goodyears harder than anyone else present. There was no competing tire products to test so about the only conclusions I could draw were: 1) the F1 GS-D3 is quite predictable, certainly more so than an old GS-C and 2) they are a pretty forgiving tire in that you could take them right up to the limit, then stray back and forth just across it, and not abruptly end up in the weeds.

It was difficult to gain much more of a subjective impression because an Audi A4 is not the best platform for testing like this. It felt quite heavy for its size, has too much body roll and an awful shift linkage. Additionally, the 30-psi cold figure was probably too low for that car as the outside fronts showed clear evidence the sidewalls were rolling under. For a more substantial impression or some kind of comparison, I'll have to wait until I can get a set of F1s on a car I know well.

The final stop in my day at Goodyear's San Angelo facility was a late-afternoon visit to the "Glass-Plate" testing facility. You all have seen images of tires, rolling across wetted-down, glass plates. San Angelo's Glass Plate facility is where Goodyear does that kind of test work. It's not often that tire companies invite media to visit the venues they use for this kind of testing, much less let them go down, into the underground lab beneath the plate and watch their engineers at work, but Goodyear did that for me. The actual plate is about 18-in. wide, 36-in long and 4.5-in. thick and is covered by an .080-in. of water. The Glass Plate control system is designed to hold that water depth accurately as long as the wind is less than 2-mph. If the wind velocity is higher than that, no testing is conducted. After each run across the plate, automated equipment cleans off the plate and restores the water layer to the .080-in. depth. The plate itself is scientific-grade glass that is optically correct. The imaging equipment is all digital and computer-controlled. Strobes are used to light the tire as it crosses the plate and the water is dyed green, which shows up best in a color image. While we were in the "Pit," a Goodyear test driver ran a C5 Coupe fitted with F1s over the plate a couple of times at 40 mph while I watched the test images get processed then looked at the results.

Goodyear supplied data accumulated at this facility for the Bridgestone Potenza S-03 PP, the Michelin Pilot Sport and the F1 GS-D3. Typically, this data is taken at 2mph (which establishes a 100% footprint "baseline"), 40 mph, 60 mph and sometimes higher speeds, depending on the tire or the testing required. In this case, the data was for 2, 40 and 60 mph. At 2mph, obviously, all three had 100% of the footprint area retained on a pass through the .080-in water. At 40 mph, They varied from 88% area retention for the Goodyear and the Bridgestone to 91% for the Michelin. At 60 mph, things changed. The Michelin dropped to 61% of the area retained. The Bridgestone was at 64% and the Goodyear was at 67%. If you want to go fast in the wet, the best hydroplaning resistance in the ultra-performance tire market, right now, comes with the new F1.

The new Goodyear's improved resistance to hydroplaning in the wet comes from something called "V-TRED" technology. Circumferential, water-evacuation channels, such as Goodyear uses on the Auquatred 3, wouldn't work on a tire like the F1 GS-D3 because they'd deal its dry-traction capability a serious blow. The solution is long, sweeping grooves that are at an angle, but not as sharp an angle as seen on previous Goodyear performance tires. What's unique is V-TRED grooves extend more than three times the length of the tire contact patch. When the tire is rotating these grooves greatly enhance the flow of water to the outside of the tire's tread, yet still put lots of rubber on the road. I prefer not to upload images with forum posts, I'll refer you to Goodyear's web site at www.eagleF1.com where there is an outstanding, graphical display of the V-TRED idea along with a lot of other pretty cool image stuff. You need the latest Macromedia Flash plug-in for your browser to view this site. Later, when I post a product review of this tire, I’ll post some images, too.

This tire, in a limited amount of sizes, was introduced over in Europe back in the spring. American car magazines seldom do tire tests these days, but tire testing is wildly popular amongst the European automotive press. In the last six months, the British magazine, EVO and the German publications Auto Zeitung , Sport Auto and Auto Bild all ran tire comparison tests and Auto Bild has run two. Each of these tests included the F1 GS-D3. In the interest of saving space, I can't list all those results but suffice to say, the new Goodyear was an outright winner in some of these tests and placed very well in all of them. My guess is, further details of these tests can be found on each magazine's web sites and, perhaps, English versions of the data may be on Goodyear's site.

At this point, I'm a believer.

On my list of tires, the new Goodyear Eagle F1 GS-D3 has replaced the Pilot Sport as the best, all-round, ultra-performance, tire. As soon as I get a set of these new Goodyears on something in my own fleet, I may have more to say, probably in the form of post to the AC’s product review section.
Thanks for the great review. I had the pilot sports on my last C5 (99 C5) and I thought the improvement was immense compared to the runflats..that came standard...

Glad to hear that Goodyear stepped up to the plate with this new rubber..

Although in hindsight I would have purchased wider rims to get larger rubber on that car..these new tires sound excellent.

Thanks for the information.

It is too bad that Goodyear can't develop a better run-flat tire for the Corvette. I purchased my C5 new and can't believe how loud and noisey the EMT tires are. In all my years of driving, the Goodyear EMT tires are the loudest of any car/tire I have used. The tire noise/whine seems to be getting louder as the tire wears.

If you have any influence with Goodyear, encourage them to develop a quieter run-flat tire for the Corvette. With the same tires being used from 1997 - 2003 (except the Z06), the replacement tire market is huge.

When it is time to replace the original Goodyear run-flats on my Corvette, I hope there is a better tire available. I don't want to replace them with the same loud, noisey tires.
I've heard quite often that as far as runflats go..the Yokohamma's are excellent choices...

The new upcoming michelin PAX system being used by the 2003 viper...and probably the new Cadillac XLR might also bring that tire/wheel option to the C5 and most definitely the C6...

Pax system will be sold by other brands besides Michelin..they are selling technology so gain greater market penetration..(this is a wheel/tire combo only..but supposedly its the best..

Maybe Goodyear will be among to pay the small royalty to michelin?

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