updated 5/11/2013
Formula 1 Tire Graining
The 2007 Formula One race in Hungary was a crazy event with
lots of weird happenings. One of the challenges facing the race
teams was tire graining. An excerpt
from my book gives a detail explanation of give-up, graining,
heat cycles, and blistering.
During the telecast of the Hungarian GP on Speed last Sunday
Steve Matchett, the former Benetton mechanic who is the technical
analyst, said, "It's called graining because the rubber
rolls off into grains. Laying down more rubber will increase
grip and help with graining."
A more accurate description would have been, "It's called
graining because the tire surface takes on a grainy texture.
The soft, adhesive tread surface digs into the track texture,
gets deformed into waves, and as sliding continues the waves
turn over wearing rubber off the upstream side of the wave. When
the sliding stops the deformed rubber snaps back leaving a peak
pointing against the direction of travel. As more rubber is laid
down during the race, grip will be reduced and there won't be
enough side loading on the tread surface to start the wave formation."
Steve is a smart, very articulate guy with a lot of experience.
The basic errors in his description of graining just shows how
complicated tires are and how much misinformation exists even,
or maybe especially, among experienced racers.
Steve could have added that a poorly balanced car maybe one
with excess understeer will grain the front tires more readily
than a better balanced car. Since some drivers need more understeer
for comfort than others, driver style can also contribute to
graining.
Graining also pops up when a driver pushes the tires too hard
before they get up to operating temperature. Rather than grip,
they slide and the tires show graining.
It would be fun to hear graining stories from racers. Photos
too.
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