What can drivers do to generate heat to tires in cold temperatures?
When you go out for the first lap of the day, you may notice that the car has reduced grip and your lap times are slower. Bit by bit, the car and driver system get into a rhythm, and you finally start putting down some lap times that you were expecting. It’s no secret that specifically the tires go through a warmup period. Formula 1 teams invest heavily in tire blankets and keep the tires at the proper temperature until the last few seconds before a car is released. But we are not Formula 1 teams no matter how much we wish we were. So, what can we do to warm up the tires while on track so that we can set some blistering lap times as soon as possible.
To put it simply, this is an energy balance issue. To generate more heat into tires, you must put more energy into them. We put energy into the tires by repeatedly loading the tires. Notice how if you take an eraser and start rubbing it on a desk, the eraser slowly starts warming up. The same principle applies to your racing tires.
We can load tires laterally, longitudinally, and vertically. So, let’s touch on each one and consider what the pros and cons are.
To laterally load the tires, we must produce a slip angle at the contact patch. How we do that is through turning your steering wheel and weaving your car left and right. This causes the sidewall and contact patch to deform laterally, and this can warm the tires up. However, let’s consider what happens at the contact patch. The lateral grip and slip angle of a tire goes through an elastic region and then a saturated region. The slip angle deforms more and more as it gets through the elastic region and when it gets saturated, the slip angle will stop deforming and just start sliding across the asphalt. This is the beginning of the saturated region. Therefore, to optimally develop heat into the system, we must utilize all regions. Begin by turning your steering wheel and going through the entire elastic region. Your steering effort will increase slowly and then your steering effort will start decreasing. This is when you have saturated the tire. Make sure the tires get saturated a small amount before you unwind the steering so that we can take advantage of the tires sliding on the asphalt to generate as much heat as possible.
In reality, I personally have very rarely seen this done properly. It is difficult even for seasoned veterans. First of all, car balance can make this very tricky to do properly. If the car is unstable by nature, you will never reach a high slip angle for fear of spinning the car (spinning the car does a marvelous job of heating up the tires). Most of the time, you will reach less than 50% tire utilization. Based on the balance of the vehicles, your tires will also unevenly heat up. If the car tends to oversteer, then the front will likely either never heat up properly since the rear slides out before you saturate the front, or the rear will overheat due to you attempting to heat up the front. You can imagine that the opposite occurs if the car tends to understeer. It’s much better to concentrate on going through the corners as fast as your tires allow and do gradual steering inputs on the straights making sure to really feel out the limits of the tire so that you can maintain tire temperatures.
Next is my favorite method of warming up the tires – longitudinally and vertically. It’s simple, just load up on the brakes until you hit ABS or right before lock up and then accelerate hard. This is so easy to do, and it does a great job of loading your front tires.
You may have noticed earlier that I eluded spinning the car does a great job of warming up the tires. The reason for this is because your tires are loaded both laterally and longitudinally. If we focus on combined loading of the tires, we can generate a lot of heat. The way we do this is by introducing steering angle while we have saturated the tires longitudinally. Begin by braking as hard as you can and then introducing a small steering angle. Slowly reduce the braking and introduce more steering angle. This will make sure that the tire stays in the combined region as much as possible. This is like trail braking, but you begin steering while saturated on your brakes. You will initially understeer and as you let off the brakes you may oversteer depending on how your car is set up. Be careful of the oversteer but because you are gradually letting off the brakes, you should be able to counter the oversteer and adjust as needed. Because of the way you vertically load the front and then transition to loading the rear while increasing the slip angle, this does a great job of more evenly loading the tires during corner entry. This is very subtle and may not seem like much, but it does a great job of heating up the tires, at times within a lap depending on the track. But ensure that you do this maneuver on a flat corner (not a downhill or uphill) to ensure stability and ensure that you do this on corners with plenty of space. Once you get on the straight, do gradual weaves and focus on maintaining tire temperatures as mentioned before.
The issue with this method is that it can be tricky to do, and you typically must be careful that you do not excessively wear your tires. Tire temperatures can be tricky, especially in cold weather and sometimes you may never reach an optimal temperature. The correct way of heating up your tires is dependent on what works for you. Both driver and vehicle are important when attempting to get to the proper race pace as quickly as possible. There are also many vehicle setup options available for improving tire temperature. This won’t be covered in this article but if you’re interested, let us know and we can write one in the future!