Information on rims:

Types of rims:
Today, rims are constructed in such a way that the tyres can only be mounted by machine. The rim has the task to keep the tubeless tyre in its place in every operational condition without any loss of pressure. There are many types of rims for passenger cars. A rough classification can be given: as for the material, there are rims made of steel or high-grade steel on the one hand, and alloy rims made of aluminium or magnesium on the other hand. In case of multi-part rims, there can be a combination of both.
In comparison to the common steel rim, the alloy rim reduces the unsprung mass, provides better ventilation for the brakes and improves the optics of the vehicle. The origin of alloy rims lies in racing sport, yet today they have become the standard initial equipment for more and more middle class cars and even cars of the lower price classes. Alloy rims of DBVAls aluminium-silicon cast with manganese or magnesium additives can be produced in especially beautiful shapes and have added to the popularity of the alloy rim. Indeed, steel wheels have also become lighter due to new developments and reduced thickness but they are used mainly for vehicles where economy is the main decisional base.
A way to optimise alloy rims (mainly by weight reduction) can be to produce the wheel disc from two or more cast parts which are connected via friction welding. One-part rims are cast from one piece (mostly by low pressure mould casting), powdered, painted silver and then clear-coated.
The two-part rim usually consists of the rim-star with the rear flange, and the front flange. The bolt heads are located in the outer connection area on the polished front disc. The rear disc with the rim-star is cast from one piece and is mostly powder-coated in grey, painted silver and then clear-coated.
The three-part rim consists of the front flange, the rear flange and the rim-star. For mounting, the tyre is not pushed over the flange, instead the discs are attached on the left and right hand side of the tyre respectively, and screwed on together with the rim-star.

Rim labelling
Exemplary for the labelling, we show the DBV rim
BISCAYA 15 7 x 15, ET 38, LK 4/100:

• 7 indicates the width of the rim (in inches)
• 16 indicates the diameter of the rim (in inches)
• ET 38 indicates the wheel offset, meaning the distance between the bolting area and the centre of the rim.
• LK 4/100 indicates the diameter of the bolt circle: accordingly, 4/100 mm in this rim means, it is fastened by 4 bolts positioned on a circle of 100 mm diameter.

Maintenance of the rim:
Salt, brake dust, loose gravel, road dust – the rims of a car are subjected directly to the environmental influences. Only by regular maintenance will alloy rims preserve their glossy appearance. There's an old saying: better to maintain regularly than to despair of the dirt just before write-off. "Prevention is better than cure". On principle, cleaning on a weekly basis is recommended for all rims.
If the rim surface has been damaged e.g. by contact with the kerb or by stone-chipping, the damaged area should be mended immediately with a touch-up pencil. Otherwise, infiltrations at the seams of the damage might occur if the uncovered aluminium starts to oxidise.
High-gloss rims should be maintained accordingly as a precaution. Hard wax is very suitable for this purpose by creating a protective layer. Then the "normal" carwash is sufficient to let the beloved wheels gleam again. Yet, what to do if it is too late, and brake dust, rust stains or blind patches mar the optics of the rims? Then you should use an acid-free rim cleaner. Observe the reaction time stated by the manufacturer, then rinse the rims with a steam blaster or a water hose, and finally dry them. For cleaning, the rims should be cool so don't clean them after exposure to blazing sunshine or after longer journeys.