How I Use Data To Tune My Car

In this video I reveal everything I’m currently doing to maximize my car’s potential – all while using data. If you’re not using data to make positive changes, you’re just guessing. And guessing, unfortunately, is the same thing as hoping.

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How I Use Data To Tune My Car – Video Transcript

Hey everybody, Matt Covert here again from and I just made a video that was all about using data as opposed to just guessing and hoping for positive change in your car. And in this one I’m going to tell you exactly what I do and how I use data to make real, quick, positive changes to my car. And I’m excited to share this with you because you don’t see a lot of these things at the track. And this stuff will definitely help you out. OK? So let’s hop right on in.

This is going to give you real, actionable, information that you can implement into your racing program immediately and those are my favorite ones and I love that. So let’s talk about what I’m doing. Number one, I don’t like that circle, I’m going to make another one. There we go. Number one. The first thing I do, and this is something I do after every single run, I take twelve tire temperature readings. And I do it like this, let’s say we’re looking down on a tire, OK? I take a reading on the inside tread, the middle tread, and outside tread.

And there’s a video about how to do this and why and why it works and I’ll link to that to you can hop to that if you want to see it. OK? This will help you find your – oh, no, this will help you stay inside your optimal temperatures. People don’t realize it but the driver has a huge amount of control over what temperature the tires stay at while he’s driving. And he needs to stay inside these optimal temperatures and that’s really important. If you go outside of them you’re either leaving grip on the table if they’re too cold you’re not driving hard enough. Or if they’re too hot you need to chill a little bit. OK?

This will also help you find your perfect tire pressures. And that’s really the important thing, the thing I use it for the most, is dialing in the right pressure for your tires, OK? The contact patch of a tire, and I know we’ve gone over this stuff in other videos, the part of the tire that actually touches the ground surface is the contact patch. That is the only thing connecting your car to the ground. If the pressures aren’t right then you’re really losing out. There isn’t much touching the ground and your pressures can help maximize that contact patch. You want the whole tread section to be touching the ground. And that’s the goal there. Mmmk?

So taking twelve tire temperatures will help you do this, like I said I’ll link to the video so you can – we won’t do that again, we’ve already done that in a video. OK?

So the second thing that I do, and this stems off of tire temperatures again, there’s so much information to be had from just reading the temperatures of your tires OK? The car’s balance. We’ll just put temps again. OK? This has helped me dial in the anti-roll bar, or sway bar, settings of my car. And I’ll show you why. A neutral handling car, there’s a video about that too, a neutral handling car has the same amount of slip in the front tires and the rear tires. And there’s a video about slip angles too. Man, all kinds of awesome information coming out. I am really excited about giving you all this free information. So I’ll link to that slip angles video as well, because that’s really important.

Let’s see. When I got my BRZ, I have a 2013 Subaru BRZ which I have been racing. I like it. There are things I don’t like about it. But since I’m in a Street category I can’t change them so I’m working with what I have. And that’s the whole point of this website, driver skill over throwing money at the car. When I first got the car, I’m going to use some theoretical numbers because I don’t have my data sheets in front of me, but I saw this all the time for the first couple races before I started dialing things in, OK? When I came off the track my front tires were always always always hotter than the rear tires. And that’s an indication that the front of the car is doing more work than the rear of the car. Because they’re producing more friction, which means more heat, and that’s why they’re hotter.

OK? And I don’t like that. Because that means the car is understeering all the time. And that’s not good, that’s not a balanced car. OK? So, because I was taking tire information I was able to see this, as well as feel it, OK? So what I did was I put a big rear bar on because nine times out of ten a bigger rear bar will help the car oversteer, OK? And so I started seeing temperatures a little closer, even within ten degrees, often. Which is great. And you could feel the difference was huge. It had better rotating into corner entry under braking. It was much quicker through the slalom sections, OK? And this is an example of using real data to tune your car. OK, without these numbers you would just be guessing.

And I’ll give you an example of – let me just do a quick tuning example. The BRZ, the Subaru BRZ and the Scion FRS are virtually identical aesthetically. OK? But the BRZ has a natural tendency to understeer and the FRS has a natural tendency to oversteer. So even though people think these corporate sisters are exactly the same, they are not. They have very different spring rates when they come out of the factory. That’s basically the only difference between them, alright? So I know a guy who has an FRS. He’s a winner. He’s an incredible driver. I look up to him and he mentors me whenever he’s around. His FRS is remarkable, he has it tuned very very well. He has a giant front sway bar to help curb that natural oversteer. OK?

So if someone is using that monkey vision that I talked about in the last video, the video of data versus guessing, if some people are just monkeyvisioning these two cars because they think they’re the same and they put a giant front sway bar on the BRZ, it’s going to make the car horrible. Because that is just compounding the natural tendency of this car to understeer. Alright? Without this data you don’t really know. Even two cars that are virtual identical – they’re not going to have the same tuning preferences. And this is something you really have to understand because this goes for anything. Someone’s Miata versus a three series BMW or whatever you have. Just because the cars are basically the same they don’t all respond to the same tuning preferences.

So keep that in mind. That’s really important. This why we use data. We’re using data because our car is unique. And just because something is working for someone else doesn’t mean it’s going to work for us. So you want to make positive scientific change based on really solid theory and strategy. And that’s what this is for, and I love this stuff, OK?

Let me go on to another one. Let’s move on to the third one. I think this is going to be a longer video than normal, but that’s OK. Tons of free information and I’m just excited to share whatever I’ve learned with whoever is going to listen so I’m going to keep on going here. OK, let’s talk about choosing tires. There are a lot of good autocross tires out there right now. And there are all kinds of people talking about it on forums. There’s a separate video all about forums somewhere. I stay away from forums. I’ll talk about that at some other point though.

So how do you know what tire to pick? OK you can talk to all the guys who have them, all the guys who like them. Ninety five percent of people who are racing autocross have only used one tire and they have no idea what the other ones are like. OK? So their opinions don’t really matter because they haven’t done any type of scientific comparison, OK? That’s why I defer to experts like The Tire Rack who, every year, they take all kinds of autocross tires and test them on the same vehicle and they give you great data plots and all kinds of information about which tire is actually better. There’s a link to a really good article they did with all kinds of graphs and spider charts and all that kind of stuff that makes me really excited. So I’m going to put a link to that so you can go see which tire is actually better.

I used the Dunlop Direzza last year. I’m going to do it again this year because it is the best, no questions asked on that one. OK? Choosing the right size tire, though, that’s up to you. Because you do have a number of options. If you’re in a Street class you can use whatever tire fits on the rim. You can go up a rim size, you cannot change the width. So you have to choose what size you want your tire to be. OK let’s use an example. My factory tire size, I think, is a 215/45R17. I’m going to go with seventeen wheels again this year OK? But I’ve got a really neat option. I’m going to jump up to the 225.

And why would I do that? This is the factory size. There’s a very good reason to do this. OK, and I’m not doing it based on a guess. I’m doing it based on data that comes specifically from Dunlop. And, I think, let me try to switch screens here. I think I can show you some real – yeah look at that, real information from Dunlop. This is on the TireRack website about the Direzza tire. See this little red dot? That shows you the factory tire size for my BRZ. Alright? And you can see over here that this is an eight inch tread width, which is good. OK? But if I hop up to the next size, which will fit on my rim. Seven inch rim. If I hop up to that my tread width jumps up to eight point two.

And while that doesn’t seem like a lot – let’s go back to the other screen here. While that doesn’t seem like a lot, let’s talk about contact patch for a second. Alright? If this is a tire, looking down from above on the tire, this is the only part of a tire here that is actually touching the ground. OK? So what we’re doing is we’re going from here to here. Last year I had an eight inch tire and now I’m going to add point two inches onto the side of that. OK? This is probably only a two or three inch section right here that goes all the way across. Adding almost a quarter inch on the side of that on all four tires is going to make a big difference.

OK? And I’m not just guessing on this either. This is something I talked to a multi autocross champion about. That’s what he did last year on these. He has the FRS. And he jumped up to the 225s and he loved it. He said that he difference was absolutely incredible. We’re talking about a ten millimeter difference here. OK? Ten millimeters? Point two inches doesn’t seem like a lot but it’s going to rock your world. And that’s really exciting, OK?

So here we have three really great examples in the Street category where you can’t really make a whole lot of changes. Three great examples of using real data to make real changes for positive improvement. And that’s what we’re striving for all the time. And I think I’m going to end there. There’s a ton of awesome information in the video. Watch this video again. It’s really long, I think it’s going to be about eleven minutes long, OK?

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