Tech Q&A: Kenny Francis

CONCORD, N.C. -- Dover International Speedway used to be one of the hardest tracks on right front tires on the NASCAR Nextel Cup schedule. Used to be, you'd see a handful of drivers plow into the outside wall after a right front went down.

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But with Goodyear's new tire, that isn't as big an issue as before. Kenny Francis, crew chief for Jeremy Mayfield, talked recently with Lee Montgomery of NASCAR.COM about tires at Dover and about getting the car to handle at the one-mile concrete tracks.

Some of the answers might surprise you.

Q: Dover has always been tough on tires through the years. Do you expect that to be a big issue this week with the softer tire?

Kenny Francis: I don't think it's going to be an issue. Dover is different. We went and tested there, and the wear is pretty high when you test. But it seems like when you get all the cars there and the track gets rubbered up with the Busch cars and the trucks, the wear goes away.

Sometimes at Dover, you can actually fight the other problem: not wearing enough and the tires get too hot. But I don't think it's going to be an issue. It looked like everything was going to be good when we tested there.

Q: When you practice without the rubber on the track, what are some of the characteristics of the car? Is it loose, and then when the rubber builds up, it starts to push? Or what?

Francis: Typically, on most tracks, when you get more rubber down, it gets tighter for some reason. I guess if anyone knew the answer, they'd win all the races. Typically, it gets tighter as rubber gets laid down. Sometimes, the exception is Charlotte or night races. Usually you have to work the whole race to free the cars up because they get so much tighter as more rubber gets down.

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Q: The right front is not the one that takes the most abuse during the race?

Francis: Actually, with this generation of tires, believe it or not, the left front is the one that gets the most abuse. You usually don't see as many right front problems anymore, which is what Goodyear did when they designed this generation of tires a couple years ago. They were trying to eliminate all the right front problems that we used to have at tracks like Dover, tracks that were such high-load, high-wear. If you got tight, you'd kill the right-front.

I don't know what they did, but they definitely helped that a lot. You don't typically see right front tires go down anymore. If you do, it's usually a cut tire or something. What they did was transfer the wear to the left front, so if you're tight, you're wearing the left-front out, and you just keep getting tighter and tighter because of the left front.

It's a lot different than it was a few years ago. You have to tune for that.

Q: Therefore, because the right front doesn't take as much abuse, can Jeremy go in the corners harder?

	Credit: Autostock

Francis: You can still get it too hot and blister it. That's what you've got to be careful about. But typically, with the cambers you run any more -- you don't run as much camber because they designed a tire that doesn't want as much camber -- so that problem's kind of gone away. You've still got to worry about it a little bit, but it's still not near the issue that it used to be.

Q: Is it more difficult chasing these tires than the older tires?

Francis: It's probably a little more difficult. You see that in a lot of drivers who have struggled, guys like Jeff Burton, he'll tell you when they changed the tire, it kind of threw him for a loop. It's kind of like a lot of things aren't intuitive anymore. What you have to do, it's not exactly the same as what you learned coming up on the short tracks. It is a little bit frustrating sometimes trying to do something that you think is opposite of what you think you should do.

Q: It is easier to adjust to a concrete track or an asphalt track? Why?

Francis: I think they're all hard. Concrete is usually less sensitive to temperature, the sun coming in and out, than asphalt. Asphalt, when it gets hot, I don't know how it's made, but it seems to get slicker like the rubber starts to get embedded in it, and then the oil starts coming out of it. It gets a little greasy feeling, where concrete, you don't seem to have a problem like that.

Concrete's got its aspects that are hard to deal with because you've got all the expansion joints in it, and that plays havoc with your tire pressures and your shocks. It's hard in that respect. They just have different tendencies that you have to deal with.

Q: Going to a concrete track, what are some things you have to do to a car that's different from an asphalt car?

Francis: Nah, we pretty much run the same cars everywhere. We don't really do anything different.

Q: You guys did 600 miles Sunday night, and then Dover. Are these the two toughest races on equipment -- and they're back-to-back.

Francis: I don't know that Dover's any tougher than anywhere else on equipment. The tough tracks on equipment, at least from the motor perspective, are tracks like Michigan or California -- tracks where you sustain really high RPM for a long time. A place like Dover, you get high RPM, but it's only for a short period of time. At Charlotte, it's just a longer race. We'll probably gear to not abuse the motor for that many more cycles. Most of the motor shops now calculate everything out. They have a cycle life for all the parts, and they've got it down to a pretty good science. They only want this much fatigue on the parts, so this is what we need to do to make it work.

Q: We're always talking about aero being so important. A place like Dover, clearly aero is important because of the speed, but is mechanical grip almost as important there as opposed to somewhere else because of high banks and high speeds in the corners?

Francis: I don't know. Mechanical grip is always important, but anywhere you're running over 140, 150 mph, aero pretty much dominates. I don't think it matters what the rules are or what kind of car you're running, if you're running that fast, you're going to have to deal with aerodynamic problems.

Mechanical grip is important, and we work on mechanical all the time with shocks, cambers and stuff like that, but the biggest places of mechanical vs. aero are places that are rough. Charlotte's a pretty rough racetrack. At Charlotte, you have to do stuff a little different than you have to, say, at Michigan -- that's a big aero track.

Tracks like Dover and Charlotte, that's a balance between the two, for sure. Dover's a lot smoother than it used to be, but it's still got all the expansion joints and all the little bumps and ripples that are really high-speed type of events for the tires. That's where tire pressures and shock settings are so important there.

Q: How important is gear ratio selection there? You're going into the corner pretty hard, and you're coming off pretty hard.

Francis: What affects people's gear choices -- and it's more evident with a tire that falls off more -- is the drop-off in lap time. Dover, historically, has a pretty fair drop in lap times. It's a second or a second-and-a-half or something like that over a run. A place like Michigan is a couple seconds over a fuel run. Charlotte's going to be a second-and-a-half, couple seconds.

It's when the speeds drop off so much in the corner is when you're struggling with what gear to run. You want to run the most gear as you can for when the speeds drop off so you're still in your torque range. But that's too much gear when you're on fresh tires, and you can overrev the motor. But you don't want to give up running overdrive or something like that because you're giving up restarts and pit road.

That's the difficult part, is the tracks where the tires wear out a lot and the speeds drop off.