Subscibe to our feedWhere the Rubber Meets the Road
In many a situation, the moment of truth is often described as the place where the rubber meets the road. That expression may not have originated in NASCAR, but it fits.
The four tires on a race car are some of the most critical components and they’re one of the few parts that can be easily adjusted from one pit stop to the next. Understanding them and maximizing their performance can make the difference in winning and losing. Few teams in NASCAR are better at tire strategies and tire management than Jimmie Johnson and his No. 48 Lowe’s team.
Crew chief Chad Knaus said one of the basic aspects of tire management is realizing that even though Goodyear Eagle racing tires may look alike and carry the same markings from the factory in Ohio, no two are exactly alike.
“Every tire has its own make-up,” Knaus said. “Each tire is a little bit different. Tires are hand made, not by machine.”
He said the rubber in the sidewall can be a little different, and the way the cords are laid during construction can vary ever so slightly. That affects the way each tire reacts under the strain of racing at speeds to up 200 miles per hour or more.
Goodyear engineers give the teams data about the spring rate and sidewall stiffness of each tire. But that’s just a starting point.
“As you increase the air pressure it’s going to react differently,” Knaus said. “Tires have become a very, very big tool, but the problem is you don’t know exactly how a tire is going to react every time. If the sidewall is different, it’s going to feel different to the driver. It’s difficult to manage tires.”
Assisting Knaus with his tire strategies is tire specialist Lisa Smokstad.
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Smokstad’s weekends at the race track start at the Goodyear tire stacks, where she picks up the first six sets of tires, the normal allotment for the opening practice sessions. More tires are issued during the weekend, and somewhere around 10 sets are made available on race day. The number of tires used varies from track to track depending on the track’s history of tire wear.
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The tires come mounted on wheels already, but Smokstad leaves nothing to chance. She sorts them according to the specifications she’s gotten from Goodyear, purges the air and replaces it with nitrogen, which displaces moisture and makes the tire pressure build more consistently when the tires are in use. And she double checks everything, right down to the attachment of the wheel weights.
“We check a lot of things the normal person wouldn’t see,” she said. “We go through and check everything.”
Once Johnson hits the track for practice, Smokstad and Knaus begin searching for the optimum air pressure to run at each corner of the car. Small changes in air pressure – a half-pound to a pound of air pressure variation in each tire can make a noticeable difference in the way the car feels to the driver.
“It’s obviously a pretty large tool that we use to tune the race car,” Smokstad said. “A half a pound here, a pound there will work on different corners of the car. Chad and I look at it as an extra spring in the race car.”
And that’s where the rubber meets the road – somewhere between the “Gentleman, Start Your Engines” and the wave of the checkered flag. And Knaus and Smokstad will be right there, ready to turn their tire strategy into a trip to Victory Lane.