Short Heat Cycles: Great Grip In Autocross

Autocross events are over in a flash. How do you get more grip with such short heat cycles? In this “Ask Samir” article, this was a question I was happy to help Peter answer below:

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Getting More Grip With The Short Heat Cycles in Autocross

Interesting stuff. Hoping for the [Master Your Tyres] online course to open up again soon. I am on the waiting list.

What can be said about short heat cycles? For example autocross/slalom where you drive for aprox 3-5 minutes at the time? How to best preserve tyres when running 10-15 short stints in a day. 

Peter

Hi Peter

Good to hear from you. Yes this is a good question. I’ve had quite a few autocross people through Master Your Tyres. Autocross is not something I’ve personally done but we’ve worked through several challenges like this to help get them more grip.

The challenge really is that with such short heat cycles you don’t have enough time to get the tyres up to temperature.  Assuming you can’t pre heat them in some way. 

It is not 100% clear what you mean by “tyre preservation” because tyres are always wearing out every run, no matter how short.

However to get more longevity out of your tyres maybe take a read of this article on bedding in new tyres [link]. This is my best advice on how to not damage the tyre early in its life which has paid me back over the longer term.

It might be that you already do this but if not I’d give it a go.

How Do You Measure Tyre Wear?

The metric I keep an eye on with tyre wear is peak acceleration values. If you run a data logger you can track these over each run to get a general idea of how fast your tyres are losing grip.

One other thing to consider, as the tyre “bulk” or tread wears down, it can no longer hold as much heat. In your case this will mean older tyres will not get anywhere up to the same temperature as new tyres in your short runs. 

The way I’ve compensated for this in the past is in a quali session where we deliberately “over inflate” the tyres, i.e. go up a little on the cold pressures, to get the tyres working harder and hotter earlier. 

Maybe that is something you could try by also measuring tread depth each run? 

Tbh pressures are your main control variable here. And temperatures are your measure of success - in your case the hotter you can get them in your run the better imho.

Start with Tyre Pressure Experiments

What I worked on with other autocross students was a strategy more around pressure optimisation.

This is in terms of both grip but also you handling balance. So what effect does it have to your driver confidence to go outside your normal range and experiment with different pressure settings?

This could be different front to rear. Individually different. All the same. Etc. 

The Master Your Tyres programme is of course all about tyres, how they work and how you can get the most out of them - as an engineer but also as a driver (they do strange things that, if you know about them, you can take advantage of as a driver.)

The bigger picture however is about this mental shift to designing experiments.

I don’t have all the answers for you. But I could find them out.

And the way I’d do that would be through deliberate experiments with different settings and getting you to drive in different ways.

The course is therefore a lot about encouraging you to be able to have the confidence to design and do those experiments for yourself - armed with a significantly more in depth understanding of what is happening at the contact patch. 

How Sensitive Is Your Handling To These Changes?

For you getting control of your tyre pressures, or even thinking this slightly differently, knowing your cars sensitivity to different tyre pressures in terms of balance, would be my first suggestion for you. 

So given how the car is handling, given how the weather is changing, given how many short heat cycles you’ve had on these tyres, aim to know: “What tyre pressure do you want to have on each tyre, and at what point in the run?”

Guide To Taking Tyre Pressures and Temperatures

To achieve this or get you going in the meantime, I’d suggest taking tyre pressures before and after each run - best you can - as well as tyre temperatures. If you want some guidance on this check out the Track Tyre Tuning Guide here. 

Quickly you’ll start to see patterns. Combining that with your experience as a driver and you have the beginnings to solve this puzzle with precision.

No more first turns wondering what car you have under you this run! :)

Hope that helps you?

In the mean time, stay on Ahead of the Curve and I’ll make sure your the first to know when Master Your Tyres opens up again. 

Best wishes buddy,

Samir