During the 337 lap / 500 mile NEXTEL Cup race on Saturday night NASCAR's stars were wrecking every 25 laps like clockwork. It seems that the tires were not able to dissapate the heat quickly enough. This lead to blistering which then lead to chunks of tire coming apart. Then the tire would completely fail and cause a wreck.
Tracking the "why"
Lowes Motor Speedway has had bumps in it for years. There was a particularly bad one in turn one that has caused many incidents. After seeing other tracks like Indianapolis Motor Speedway have success with the process Lowes track owner Bruton Smith decided to "levigate" the track.
Levigation is a process where basically they take a big grinder and grind down the bumps in order to smooth out the track. This is a process that has worked well at other tracks and seemed to be an ideal fit for Lowes' bumps. It's hard to blame Bruton for deciding to levigate.
There is one primary side effect of having fewer bumps. The smoother surface allows speeds to go up dramatically. The track record for qualifying went up over five miles per hour from last October's record setting run.
What we saw on Saturday night was that higher speeds generated much higher tire temperatures than Goodyear predicted and the tires were failing.
This is a simplified version of the problem, but it gets to the heart of the issue.
How come nobody knew?
Even with all of the technology available today nobody really knows for sure just what is going to happen until the teams unload and get on the track.
Tony Stewart and Greg Biffle were among drivers that tested at Lowes Motor Speedway a few weeks ago. Both of those drivers crashed, twice each. Those incidents were not because of tire failures, but rather because the racing groove, or ideal driving line around the track, was very, very narrow. The narrow groove was because not many cars had driven the track to put rubber down on the track.
Based on those real world test sessions Goodyear felt that they had the right tire for race weekend. It's hard to fault Goodyear for basing their decision on real testing in addition to their computer models.
As a result of those testing crashes Bruton Smith had trucks go out and drag tires around and around the track to put down rubber and widen the groove. While this made the track less treacherous, this had the side effect of increasing speeds even more.