TIRE MANAGEMENT ON THE TRACK: THE EXPERT’S TRICKS

WITH A LOWER PRESSURE, THE TIRES PERFORMANCE REMAINS CONSTANT

As all kart drivers know, tires are an essential component of the kart. Not everyone, however, knows how to make the most of their potential. Stefano Mantese owner with the brother Paolo of Vega, a historic Italian company leader in the manufacturing of kart tires, comes to aid all the enthusiasts. Thanks to his extensive experience, there is definitely not a more competent person to explain what the correct procedures to follow on the track are in order to manage a kart’s tires in the most precise way.

1 Do the “things to be done” begin before mounting the tires on the kart?

Yes, first of all it is necessary to measure the circumference of the new tires with a measuring tape. If the difference between the tires is 4/5 mm there is no problem. Otherwise, it is necessary to place the bigger wheel on the side which remains on the outside in the corners with respect to the direction of travel of the track. This operation helps to prevent the kart from sliding outwards. Basically, with the wheel with a larger diameter on the bearing side, the inclination of the kart will be inwards, providing greater grip on the in the middle of the curve. It certainly is not something that you feel very much. Less experienced drivers can also avoid this expedient and be careful only if the difference between the tires’ diameter exceeds 1 cm.

2 How should I adjust the pressure during open practices?

The maximum yield of the tires is obtained with the lowest possible pressure. For example, with the “Vega White”, it can reach up to 0,45 bar. The important thing is to always use the lug nuts now present on all the rims available on the market. With lower pressure, the tire performance remains constant during the practice seasons. Lowering the pressure is particularly important if during the open practice one has to go through several rounds, as by doing this, one limits the tire wear to a minimum.

3 If, once back in the pits, the pressure on the hot tires have different values, what do you do?

Indicatively, if there is a difference in pressure between the two front and the two rear tires, it is necessary to adjust them, always based on the data recommended by the manufacturer. Let us take as an example to understand this in a better way. If at the end of an open practice session the pressure is 0.78 for the front tires and 0.82 for the rear ones, we should not make the mistake of lowering the pressure to 0.78 on the rear tires too while they are hot, because at the time of the restart we will have too low a pressure and we will have no grip in the first laps, an important factor if we have to race a heat. The important thing is to stay in the window recommended by the manufacturer. If, for example, this window is from 0.80 to 0.84 while hot, we could lower the rear pressure by 0.02 and always raise the front ones by 0.02 to fall within the proper range.

To be thorough, if we manage to stay towards the lower values within this range, we can make the most of the tires.
The values recommended by Vega range from 0.78 to 0.82 so, to give another example, if we had a hot tire pressure of 0.78 at the front and 0.80 at the rear, we could leave everything unchanged as we are within the indicated range.

4 If while driving the kart starts to slide, what can I do to increase the grip? Is it better to stop or stay on the track?

The best thing is to stay on the track and let the tires cool down. We can achieve this by going fast on straightaways and taking on narrow corners normally, while on fast curves we should not force it, so as to prevent the tires from sliding and overheating, thus raising the pressure and decreasing the grip. After a couple of laps done like this, the correct grip of the tire should have stabilized itself. If the kart starts to slide in the qualification rounds, when the minutes available to let the tires cool down are limited, it will be necessary to try to drive as cleanly as possible in high-speed curves, avoiding exaggeration. Aggressive driving in fast corners can make you gain 5 thousandth of a second, but it significantly raises the tire pressure, jeopardizing the grip. This would lead to a slowing down in driving the track section, easily losing a couple of tenth of seconds. Therefore, better to lose 5 thousandth of a second earlier than 2 tenths later.

5 Between magnesium and aluminum rims, which type should I choose?

Optimal tire performance, especially in the summer, is achieved at lower operating temperatures. Consequently, magnesium is better as it is a material with good heat dissipation ability and keeps both the tire and the air inside it cooler. Aluminum rims, on the other hand, are recommended at low atmospheric temperatures because they help to quickly increase the tire pressure, which is advantageous when one needs to generate grip quickly on cold asphalt. The shape of the rim is also important, with the same material, as perforated rims offer better heat exchange than solid ones.

6 How should I drive on a wet track?

On wet asphalt, with rain tires, we can set a higher pressure on cold tires than with slick tires. Do not exaggerate: 1.2 bar is the maximum value not to be exceeded. Rain tires have a softer tread compound, designed to generate grip in colder weather conditions. To speed up the time for the tire to get to the proper temperature, I recommend using a set of aluminum rims.

7 Is it important to know the temperature of the tires?

It is important because inside the tires there are resins, polymers and oils which offer the best performance in a certain temperature range (the values vary according to the brand and model). Beyond this range, the tires’ performance declines. Therefore, by measuring the temperature, one can understand if the tire has reached its performance limit. For example, for the tire to perform at its best it must not exceed 115 degrees and, as soon as the driver stops we measure a higher value, we understand that the tire has degraded, worsening the performance by 3-4 tenths per lap.
The degradation of the tire is also important. A new tire heats up more because it has a thicker tread than a used tire. This should be taken into consideration when assessing the temperature of the tire.

TIRES OFFER THE BEST PERFORMANCE WITHIN A CERTAIN TEMPERATURE RANGE. IF THEY EXCEED IT, THE PERFORMANCE WILL DECLINE.

8 How can we measure the tires’ temperature?

It is best to avoid measuring the temperature with a laser gun as it does not provide proper data. The internal heat of the tire, when it comes out, increases the tire’s surface temperature, distorting the data detected by the gun between the first and last tire even by 10-15 degrees.

I recommend using the pyrometer, a device with a needle to be inserted on the tire tread at a depth of about three millimeters. The temperature inside the tread band, in fact, is more constant and allows it to be detected for 40 seconds, which provides enough time to check all four tires.