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 MG BRAZIL WEBSITE Tyre Tips back to MG page Wheels - Tools - Safety - Dismount - Mounting - Air Pressure - Balancing - Temperature - Storage 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, wherefore 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. back to top
TOOLS 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.
SAFETY 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.
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, insert soap on the bead. back to top 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 gauge the tire according to the air pressure previously indicated for the type of rubber and the track conditions. back to top 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.
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.
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