Tips

Wheels

The material with which the wheels are produced has influence on the temperature the tire reaches with its increasing number of laps. Magnesium is more porous than aluminum and has a greater tolerance to heat, fore the tires temperature is maintained on a more constant level. On the other hand, with the aluminum wheels, the temperature rises and there is a consequent increase of air pressure during the course of a race, such factors must be taken into consideration at the inflating process of the tires. Safety screws are mandatory on international competitions and their use is extremely advisable in those situations that utilize air pressure below 13 PSI. Such screws have an un-jumping-off function and are extremely indicated, particularly in kart circuits with high-speed turns and the asphalt with too much rubber on the ground. The geometry variation and the wheels dimensions also influences directly on the tires achievement.

Safety

Only trained people should mount the tires, wearing safety equipment (goggles) and following the necessary precautions. Never inflate the tire beyond the maximum air pressure recommended by the manufacturer. In case of difficulties to mount a tire, dismount it, repeat the mounting procedure, and check if the wheel shows any problem. Never stay close to a wheel during the inflating process. In case of explosion, the wheel fragments may cause some injuries. Make sure that the tires are properly mounted on the wheel after the inflating process, checking for possible leakages. Make use of an inert soap and verify if some air bubbles start to appear, particularly around the valve stem. Before you test the tire, make sure that there are no cuts, punctures, or rubber anomaly, especially if the tire has been previously used in another race.

Tools

Kit for mounting and dismounting

It is advisable to acquire some very useful equipment to mount and dismount tires: tire dismounting tool, valve disassembling tool, leather or metallic belt, balancing tool, inert soap to help mounting the tire, air pressure gauge and, of course, an air pressure pump at your service.

Dismounting Instructions

To completely deflate the tire it is recommended to remove the valve inside the valve assembly with a valve-disassembler tool, a small and useful equipment which has a point with a rabbet that is fixed to the valve. It is also possible to deflate the inner air simply by pressing the valve and considering the amount of air still inside, but this will make the process a little bit slow. In some wheels, particularly the ones made with magnesium, and used in important competitions, near the outside tread, in radial position of 120°, there are three fixed screws with a function to prevent a jumping-off from the wheel. Such screws are almost indispensable on tracks with extreme high-speed turns or low air pressure tire inflation. Without them there may occur some deformity on the tire bead with a risk of separating the wheel from the bead. It is necessary to unscrew it almost completely by tensioning, to avoid protuberances that may form inside the wheel channel and prevent any hampering to jump off the tire. Right afterwards, place the bead breaker over the tire sidewall near the wheel rim and press it in several spots until the tire bead gets loose. Then after the wheel is turned to the opposite side on the dismounting equipment, repeat the operation, taking care to avoid any crush to the wheel rims. Press the tread band toward the outside, attempting to fold the side of the tire to the back of inside wall until reaching half-circumference (Fig. 1), with one hand, hold the wheel and fold the tire on the upper part. With the other hand, impel the wheel to get inside the tire (Fig. 2). Afterwards, spin the tire and impel the wheel to get outside using, if necessary, inert soap on the bead.

  

Mounting instructions

For the mounting operations, you just have basically to reverse the procedure for the dismounting operation. To re-mount the tire it is useful to lightly brush a humid soap and pass it on the beads (Fig. 1). Do not make use of any other products, like lubricants or grease. Before you start mounting, it is necessary to check the rotation side of the tire and make sure you are mounting it on the correct sidewall. Then position the tire with the rotation arrow correctly and place the inner part of the wheel by pressing and spinning it, while the tire is mantained without any movement (Fig. 2). To this extent, the next step is to put the tire\'s inside face. This is done folding the tire inside wall and impelling it inwards (Fig. 3). Place the wheel with the inside wall up, hold the wheel and the tire with one hand, and with the other hand impel the tire inwards (Fig. 4). Next, to push the tire over the lip of the wheel, place it in start-up position and inflate with an air pressure greater than the one used for tests, 42 to 56 PSI, at most, to allow a rapid inflation (Fig. 5). It is useful to remove the valve (if it has not been done before) so that after the tire is pushed over the wheel the air may more easily flow out, avoiding this way any deformation to the tire. The core of the tread band, the one that under pressure may originate a deformation, is wrapped in a metallic belt, which has a closing system; or in a tightly closed belt, to avoid any tear of the fabric and facilitate an approach of the heels to the bead. This is a very delicate phase due to the not so far-off risk wheel exploration. Some companies prepare safety packages where the wheel is wrapped during inflation under extreme air pressure, able to withhold fragments of a possible and unwanted explosion. In any event, it is indispensable to protect the eyes with plastic goggles of safety type and keep the face away from the wheel as much as possible. When the tire is pushed into the wheel, replace the inflating valve and afterwards auge the tire according to the air pressure previously indicated for the type of rubber and the track conditions.

   

 Air Pressure

*Tracks with little adhesion usually require a higher calibration. At first start, it is thoughtful to inflate with air pressure between 13 and 15 PSI (hot tire).
*But in circuits with too much rubber on the ground, a usually situation when there are many karts in the track, it is advisable to use a lower calibration (10 a 13 PSI) with hot tires. 
*Weather changes have influence on the kart's behavior.
*Tires with a softer compound may require a calibration lower than the one used in tires with a harder compound.
*The air pressure gauge used to measure the tires pressure and is a fundamental equipment among the tools of any kart team. You should invest in one excellent air pressure gauge and avoid any tumble or misemployment to keep it in perfect serviceable conditions.

Tire Temperature

The karting tires are designed to reach the best performance levels when the tread band works in a temperature ranging between 80 and 95 C (176 and 203 F) degrees. The pyrometer is the indicated tool to measure the tires temperature.
It is import to mention that the karts set-ups or adaptations in the driving style may determine and help the tires to work at a stable temperature, leading to a performance peak and avoiding an untimely wear.
The type, conditions of every asphalt, and the features of every circuit also have a straightforward influence on the temperature attained by the tires.

Balancing

Balancing of the wheel/tire set is of fundamental importance to reach the best achievement of your kart. Unbalanced wheels can affect on vibrations, driving comfort, excessive tires wear, and lower achievement.The balancing of one kart wheel is of static kind, with one wheel standing on a wooden rack, without utilization of balancing machine. The front wheels can be balanced with the tire assembled on the kart, while the rear wheels need the support of the balancing equipment. The ideal balancing depends on the equilibrium of the set weight and it can be noticed when, after several rotations, the wheel always stops in different positions. Make use of a self-adhesive balancing lead weight to balance it, wiping off thoroughly the grease before the weight is definitively attached.

Storage

Deflate completely the tires after a practice or race to avoid deformation caused by the rubber high temperature. Many times the same set of tires is used more than once in a succession of races and such procedure prevents unpleasant surprises or harsh changes in the kart's behavior.