Speed Secrets: Jeff Braun on Tires
Image from thedailysportscar.com. Jeff Braun is currently the lead race engineer at Core Autosport competing in the IMSA DPI class. His CV is quite substantial; going from SCCA club racing to being the lead race engineer for quite a few successful IMSA, CART and Grand Am teams for more than 20 years. He has won seven Sports Car championships along with the Daytona 24 Hours, seven Sebring 12 Hours, and four Petit Le Mans. With fellow engineer, Paul Haney, Jeff wrote the racing engineering technical book, Inside Racing Technology. This is re-posted from Speed Secrets Weekly #311. To subscribe for more weekly Speed Secrets content, visit speedsecrets.com.
One of the first BIG lessons I learned as a driver was how critically important tires were. What I'm really talking about is having an understanding how they work, how to treat them, and how to learn from what they were teaching me. When I was writing my very first Speed Secrets book, the first Speed Secret I started with was, "You will never win a race without understanding how tires work." The rest of the book followed from there.
One of the other huge learning moments for me was understanding how impactful it is to have the right people around you. When surrounded by super-smart, forthcoming people, even I can learn and get better! One of those super-impactful people that I happened to luck into meeting is Jeff Braun. Having Jeff as one's engineer is a dream come true, as he's not only one of the most knowledgeable race engineers in the world, but I know he's the very best at sharing with others what he knows.
With tires, great people, engineering, sharing and learning in mind, enjoy Jeff's random observations below. And appreciate that his random observations are like most people's intense study and research paper… put into everyday, useable language.
P.S. – Jeff has been sharing his "random observations" on his social media accounts for the past year or so. If you've read them, you know how insightful they are (if you haven't, follow him on Instagram, Twitter and Facebook). The good news is that he's agreed to share some special random observations with readers of Speed Secrets Weekly on a randomly regular basis.
Random Observations About Tires
by Jeff Braun
Random observations on high performance and race tires and how they are being used by many amateur drivers and crews, from a sports car engineer who has made all these mistakes (and many more) and continues to make mistakes with his tires. Every. Single. Weekend. So, I really don’t know “how” to do it. I’ve just had enough time to do it wrong – a lot. (Ed. Note: Jeff is also much too modest.)
- The tire that produces the most grip – for at least one foot longer than your stint or race – is the best.
- There is no substitute for high-grip, new tires. You will get beaten by a driver who can afford to run new tires each race, assuming they follow #1 above.
- People so often try to set up a car on worn-out tires and fool themselves into thinking they learned something, when in fact they “learned” something that’s wrong. Now instead of just not knowing the answer, they “know” the wrong answer. That’s MUCH worse.
- No one can tell you what the “best” tire is for your 2008 Range Rover Time Attack car with the “twin turbo extra boost kit” and the “special deluxe aero package” that you’re taking to the Drift Nationals in Moab next week. Best advice is to see #1 above.
- If you can’t afford to abide by #2, you will get beat by those who can.
- People get pick-up (clag, build-up) on their tires and get scared because it feels like they have a flat and have zero grip. And what do they do? Slow down. And that only makes it worse. I see the pros get more aggressive in the right spots and work very hard with the steering wheel and brake to clean the tires – they scrub the pick-up off the tires. It’s not easy, but the people who slow down never fix the problem.
- Very few drivers can actually “feel” the tires. By that, I mean on a detailed level – like feel the outside front tire start to make grip as you turn in; then feel the slip angle build; then feel the load in the hands and make small pressure adjustments to the wheel based on those loads in the hands; then feel the tire start to lose grip with a slight vibration in the hands; then know that’s the limit and make a change with the wheel or brake before the tire goes over the limit and really slides and kills the whole corner. The small group of people who can do this? They are ranked as the best in the world.
- I see too many people worried about what anti-roll bar or springs or cool shocks to get when they need to focus on #7 first, before any of that other stuff matters.
- There is nothing better for learning than running on old, worn-out, no-grip tires. Understand #2 above is for winning, but “old-tire practice” is for getting better so you can win.
- People really struggle with getting their tires to come up to the hot pressures they want. It’s so simple, I just don’t understand why people struggle. Start with the pressures too high when the tires are cold (high enough so you are sure they will heat up past what you are targeting for your hot pressures), go run some laps, come in and bleed the tires down to the target pressures, go run more, and at the end of the session, stop and bleed down to the target pressures. Now, let those tires cool in the shade right next to your set of new tires. Read the cold, cooled down pressures from the 1st set and put those pressures in the new set. Now, either set will produce the desired target pressures on the car. Just never lose the “sample” set pressures and you can leapfrog multiple sets like this.
- So many people don’t get the “good” out of new tires. They go the same speed as on the old tires and can’t figure out why. See #7. That’s why.
- People forget that tires are springs with no dampers on them. Pump up a tire and it gets stiffer, just like installing a stiffer spring.
- The air in a tire is what gives it structure; not enough air and the sidewall overheats because it flexes as the tire rotates, compressing it between the wheel and road. Pretty soon, the sidewall tread joint fails and the tread comes out, leaving you with two sidewalls to use to get back to the pits. Ouch.
- I see people who think street tires with the same rating, size, and DOT markings are all the same. That’s like saying all grass-fed USDA 8 oz, ribeye steaks taste the same. It’s all about the preparation and ingredients, just like tires.
- Softer is not always better. Remember the qualifier in #1 – a tire that lasts one foot longer than your stint. Tire grip changes every lap. The goal is the max grip over the course of the required life of that tire. Soft tires may fall off too soon and a harder tire may give the max grip across the desired time frame.
- I see people forget that the tire is likely the single most important and influential component of the mechanical grip and handling on the car.
- Heat cycles affect a tire more if that tire is closer to an out-and-out racing tire. People worry about heat cycles on a tire that’s good for 20,000 miles on the street car…that’s not important. However, on a high-performance race tire that’s good for 150 miles, one heat cycle will cost you a lot of grip.
- I wonder why people don’t use the tires to tell them about their set-up or driving? Accurate tire pressures will tell you if you’re using the fronts harder this session or if that rear anti-roll bar change helped or hurt. It’s easy to read tire pressures, but people ignore it and that’s a shame.
- Race tires are expensive….see #2, though.
- The best drivers are great on worn-out or end-of-stint tires, and then use every bit of the new tire grip. Why? See #7.
- Karting is a great way to learn about tires. Why don’t more car racers go to the kart track and work over and over on #7? Could be the best money spent! Forget that new exhaust or data system. Learn how to feel the tires.
- Wonder why people don’t even look at their tires and see what the surface looks like, then try to relate that to how the car handled? Everyone has a camera in their phone…seems strange that drivers on a track day or club event are not taking pictures of the tires to go with their post-session notes.
- I see people take the checkered, do a “cool down” lap to the pits, then check tire pressures. That is a total waste of time. There are no cool down laps – the in-lap should be the best lap of the weekend until the pit entry for many reasons, not the least of which is that the tire pressures will actually mean something!
- Why do people buy rain tires then decide to not go out on track when it rains? Because it’s unsafe or they may damage the car? Rain driving is the best thing for #7 and heck, you’re going slower, so anything you hit will be at a lower speed and thus not as dangerous. Big missed opportunity by so many people. When it rains, the track should be packed with people learning and working on #7.
- People take tire temps and think that is so important, but fail to understand what they’re doing. The temps only show you a small indication of what the tire did on the last corner before the pits. That’s it – really not super informative. For sure, it’s pretty much useless to say that your tires are running hotter than last week if you’re at a different track where the pit lane is longer or shorter or the last turn is not as tight. You are seeing a small slice of information – very small – and it’s a bad idea to base your set up changes on 2% of what the tire is going through. The best thing to do is take good tire pressures immediately after coming in, as they change more slowly than the temps do. So tire pressures give a better indication of the work load of each tire – then see #22 and do that.
This is how I see it and what I observe people doing with tires. I learn more about this stuff every day I spend at the track, so I could be completely wrong, here.
– Jeff Braun
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