Michael Waltrip's NAPA crew surveys the aftermath of tire failure (foreground) at Homestea
There are plenty of changes in the 2004 Nextel Cup series, but one of the biggest is the wholesale revision of Goodyear's tires. Think about it-almost every action of a Cup team is geared to getting the optimum performance out of those four tire patches for the longest amount of time. Plus, the teams have how many gigabytes of data accumulated about how their '03 tires behaved? NASCAR and Goodyear pressed the Reset button on all that data for 2004, so we've put two of our SCR contributors on this important technical issue. First Mark Whitney details the how and why of Goodyear's tire changes, and then Jerry F. Boone reviews their first use at the last race of 2003 at Homestead.-Glen Grissom, executive editor
Part 1:Pressing reset
For the 2004 NASCAR Nextel Cup season, the rules will be reducing the amount of downforce the cars can produce. With this in mind, NASCAR and Goodyear have been discussing changing the grip on the tires. Whenever a change in overall downforce for the series is made, a re-calculation of the tire performance must also be completed to provide the teams the best tires for the conditions.
The changes that NASCAR and Goodyear are making in the tires and aerodynamics for 2004 are significant. Often we hear teams and drivers say they put the same setup under the car that they had the previous year. Also, teams keep a very extensive setup book, which details chassis setup, weather conditions, and driver comments. With these tire changes for 2004, those books become very large table coasters for a cold adult beverage. With significant changes in tires and rumors of further aerodynamic changes, the setup books will provide trends that the teams can look to, but not a baseline setup that will provide a solid starting point. These tire changes, therefore, put a premium on testing, computer simulation, and crew chief creativity.
In the 2003 configuration, the Cup cars had high downforce, and the tires, which Goodyear supplied, were relatively hard and would last. With high downforce, if Goodyear had too soft a tire, it would grip very well for a short run, but would wear out quickly during a longer run. In a low downforce car, if the tires supplied were too hard, the cars would have a hard time making it through the corners. The cars would slide up the track; nevertheless, these tires would last a long time. It is providing that critical balance, between grip and wear, that takes a lot of engineering time to design the tire construction, backed up by on-track testing time, to verify results.
Goodyear's David Blakely stuffs an inner liner into one of the tires used at Homestead in
NASCAR and Goodyear have been working together to put the best show on the track. "As NASCAR reduces the downforce, we can make a tire that is more attractive, to make the whole package [aerodynamics, handling, g-forces, and tires] work together to accomplish what is wanted," explains Phil Holmer, Goodyear's marketing manager for stock car racing.
Some of the changes made for the '04 season will be obvious and discussed throughout the sport, while other changes will be seen only by tire engineers or team statisticians. Here we will detail some of the bigger ones.
New Tire Constructions
The largest and most widely reported change is that there will be new constructions for every tire on every track raced next season. "From Talladega down to Martinsville, every track will have new tires that have been re-compounded and have new constructions," says Holmer.
A tire's construction is defined by many factors, but the easiest to describe are the thickness of the tread patch and the makeup of the sidewall. The thickness of the tread patch is important because it makes the tire stronger and more puncture resistant. However, on tracks where extreme heat is put into the tire, from high-stress cornering or setup issues, a thick tread patch is a hindrance because it will hold heat in and eventually create blisters.