AMV KART WHEELS: THE DEFINITIVE BUYING GUIDE
15 models destined for the racing world, including “Senior” Direct Drive and Shifter classes rather than the MINI (without considering the offer for the rental market): all different in terms of materials, level of grip they offer, sizes … TKART explains the articulated and fascinating world of wheels designed and produced by the Italian company
A prominent brand among companies that deal with the production of kart components (wheels, hubs, axles, etc.), AMV bases its success on a production chain consolidated in over 30 years in business. It is precisely some fundamental steps of this production process that distinguish its flagship products, kart wheels.
Design, development and production: the first steps for AMV wheels, without yet being mounted on the karts of kart drivers, are all carried out within the walls of the Italian company. In fact, the production of these components follows a very specific process: each new project is carried out by the technical department using CAD software, thanks to which it is also possible to calculate the volume of air between the tyre and the wheel, thus defining the section of the wheel. Subsequently, if the design is convincing, the wheel is 3D printed, in order to be able to practically evaluate every aspect and identify or correct any critical issues. Once the prototype has been launched, the next step is the CAD design of the mould, its CAM processing and its CNC machining. At this point we proceed with the first castings called “pre-series” in order to allow the adjustment of the mould. Then follows the casting of the first models to be tested on the track. On the basis of the results obtained, we then move on to make slight changes to the moulds that allow the casting and production of advanced wheels to be tested again on the track. This process is repeated until an optimal solution is reached. Finally, after passing all the technical checks, the actual production of the wheels takes place (which also includes their treatment and completion with valves, adhesives and packaging) and subsequent marketing.
Casting is certainly one of the phases of the production chain of which AMV is most proud. Partly because they have a foundry over which they have complete control which is unique in the world of karting and partly because the Stefanello family company has refined a particular technique for processing materials: low pressure casting. (to learn more, read “How to – How kart wheels are made”).
Another distinctive feature of AMV products is undoubtedly OXiTECH treatment, a particular type of processing (patented) designed specifically for magnesium. This process allows this material to obtain extraordinary characteristics of protection against corrosion and wear and, moreover, also gives it greater resistance to abrasion that is usually created during the assembly and dismantling phases of the tyre on the wheel (for more information, always refer to the article “How to – How kart wheels are made”).
THE MEASURES TO KEEP AN EYE ON
With regulatory impositions and the constructive choices of each manufacturer, there are several structural measures to refer to when deciding to purchase new wheels. Here are the ones that most affect the kart’s behavior on the track.
That is, the distance between the inner and outer section of the wheel. The FIA regulation imposes “limit” measures. Specifically, for the OK, OKJ and KZ classes (which we will identify as “senior”): 135 mm at the front and 215 mm at the rear for dry wheels; 130 mm at the front and 180 mm at the rear for wet wheels (since wet tyres are narrower to “cut across” water better).
As for the MINI classes, however, the limits (for wet and dry) are set at 120 mm for the front and 150 mm for the rear. In this regard, AMV has made choices dictated by the experience gained over the years: in particular, most of the “senior” dry wheels measure 130 mm at the front and 212 mm at the rear; the wet ones, on the other hand, are the same as the regulatory limit, which is 130 mm at the front and 180 mm at the rear. As for the MINI classes, on the other hand, different widths are available based on the model and type of attachment of the wheel to the hub.
Commonly the term offset indicates the distance, in millimetres, between the central plane of the wheel and its fastening point to the hub. For AMV, on the other hand, by internal custom, offset means the distance, in millimetres, between the flange fastening the wheel to the hub and the internal section of the wheel. This is a measure free from regulatory constraints and which is defined at the discretion of each individual manufacturer. This data, in fact, directly affects the torsional capacity of the wheel. To be clear, increasing the offset increases the rigidity of the wheel which, in turn, increases the level of grip that the kart will have on the track, especially when exiting bends. This is why it is customary to combine wheels with greater offsets to shifter karts (where the search for grip is generally preferred to smoothness, unlike direct drive classes) and to track situations with fairly low levels of grip. It is also important to underline that, with the same wheel width, different choices in terms of stiffness (therefore different offsets) also affect the flexion of the ends of the axle, or of the spindles, in relation to the front wheels.
Generally, however, when we talk about offset we refer more to that of the rear wheels, since it is the variations on this axis that are most noticeable. In fact, at the front the variations of this parameter are such as not to generate huge differences in terms of the final behaviour of the kart on the track.
With this measurement we mean the thickness (in millimetres) of the material the wheel is made of. In fact, this parameter affects the final weight of the wheel, its structural strength and also its ability to dissipate heat. All AMV wheels have a standard thickness of 3 mm, for both senior and MINI models, because the Italian company believes that this value allows the best possible compromise.
It is the diameter (in millimetres) of the hypothetical circumference that passes through the anchor holes of the wheel to the hub. Also in this case there is no regulatory imposition, even if we are faced with a rather standardised measure, which in most chassis manufacturers is set at 58 mm. The only exception are CRG karts, where the PCD is 67 mm.
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