Rims: Between eyecatcher and safety
Nowadays a rim is, besides its technical function, mainly an eyecatcher which visually upgrades a car. Altogether there are three different types of rims that differ in the basic materials they are made out of. There are steel and alloy rims as well as rims made out of chrome. They all have typical characteristics, which militate either for or against them. Broadly speaking, alloy and chrome rims are more popular but also more expensive than steel rims. The higher popularity results from the appealing look, the higher price from the fact that rims made out of light alloy need more materials and that the production is more complex in general. This also leads to alloy rims being heavier, so that they have an increased longevity, and with that, original advantages such as fuel savings or a better braking and accelerating behavior are no longer present. Better suitability in winter, an advantage of the steel rim, is also gone with this aspect.
Steel rims: What is special about them? How are they maintained?
The two biggest advantages steel rims have over alloy and chrome rims are the sturdiness and the worthwhile price. The more favorable price is also one of the main reasons why they are often used during “winter” season in the UAE. Compared to summer season and transition periods, this season is only a few months long. Therefore the purchase of more expensive rims made out of light alloy or chrome is only profitable for enthusiasts, as they can only be used for a short period of time before they have to be exchanged again. One of the disadvantages on the other hand is that rims made out of steel tend to rust especially when used often in winter time, which downgrades the whole care visually. If this has happened to you, the only way out is repainting. With just a few steps, this can also be done independently:
First of all remove the old paint from the rim. This can be done in different ways. A sand ray cabin, which is however very expensive, the significantly cheaper sand paper, whose use is yet connected to a lot of work, or a drill attachment can be used for this job. When dealing with tough rust a wire brush attachment should be used. Residual paint should only be sanded off. The rim can be sanded off using wet sand paper with a medium granulation (ca. P400) to ensure the subsurface remains even. Afterwards thoroughly remove sanding dust and other dust from the rim. Therefore either use cellulose thinner or silicone remover.
Care has to be taken that no other chemical or abrasive detergents are used as these can damage the coating layer. Subsequently prime the rim before you start coating with a two-component filler, like epoxy resin. Following this, the rim should be wet sanded with fine granulation (P600 to P800) sand paper again. Pick a color and paint the rim. Do this in several layers and in the course of it keep the spray can or gun in constant motion to avoid ugly paint runs. Apply clear paint for sealing afterwards. Pay attention to the compatibility of the different components (primer, paint, and clear paint) you have been using to avoid undesired reactions.
Tip: Instead of painting the steel rims you can also use powder coating. While they are extremely resistant, they are also much more expensive than paint-work.
Chrome rims: How to care for them and what to take care of?
Maybe the biggest difference between chrome rims and steel rims is that these are not painted and polished but galvanized to get their distinctive shiny look. They are, as well as alloy and magnesium rims, members of the light alloy rims segment, even though chrome is considered a transition metal from a chemical point of view. One advantage over painted rims is that they are extremely resistant when it comes to hot brake dust, which tends to brand them quite often. Because of their high stiffness brushes and clothes normally can’t cause any damage. This stiffness in particular however creates a certain shock sensitiveness, which can lead to damage by curbsides and guide rails in the car wash. Consider the following things when using chrome rim cleaner:
Do not use conventional rim cleaner!
Refrain from abrasive cleansers here as well. Normal rim cleaners also contain abrasives which take the shine from the surface.
Rather use lukewarm water!
In fact a clean cloth and some warm water is all it takes to clean a chrome rim. Detergent or chrome polish can be used instead as well. The latter often removes troublesome flash rust on top of that as well.
Tip: Make sure that the chrome plating of the chrome alloy rims was really achieved by galvanization. Some dealers offer chrome alloy rims with SLC-coating. This is a special powder coating which does not meet the same quality standards.
Alloy rims: How are they cleaned and what is special about them?
Rims made out of alloy, just like chrome rims, are mainly purchased for visual aspects. At the moment they enjoy great popularity in the tuning scene and originally they were used because they were lighter and therefore improved the comfort, they also reduced the wear of dampers and wheel suspension. Meanwhile more material is used when creating alloy rims, so this advantage disappeared. Their biggest enemies are the usual aids used to treat glaze on roads, loose chippings and thawing salt. Moreover attention should be paid to avoid hitting the curbside, as this can lead to ugly scratches and even hairline cracks. The same holds true for chrome rims, whereas steal rims are more robust. Nevertheless alloy rims can be repaired independently, if something happened. Proceed as follows:
Clean the damaged area of the alloy rim with cellulose thinner to make the damage more visible. Afterwards sand off the surface with coarse sand paper, granulation about 240. Then sand the alloy rim off with a finer granulation of about 360 and blow the entire dust off or carefully use a vacuum cleaner. Mask off the surrounding areas thoroughly and especially protect the tire, which can suffer damage because of the paint and sanding procedure. Now fill the damaged area with some repair filler and burnish it afterwards. It is important, that you read the instructions of the filler, as it has to be mixed in a special mixing ratio. Let the result cure afterwards. As a rule of thumb: Rather wait too long than not long enough! In case you are not satisfied with the results simply repeat the whole process.
Painting alloy rims singly
It is also possible to paint an alloy rim singly. Various equipment will be required:
- ideally a mounting machine
- sand paper with different granulation (ranging from coarse to very fine)
- primer suitable for alloy
- rim paint
- clear paint
- dust mask
Now follow these steps:
- Polish the scratches off!
Little scratches and scrapes can be easily polished off with sand paper (granulation: P240). But be careful. Scratches can under no circumstances be deeper than 2 millimeters. Because if a hairline crack exists, the whole rim has to be exchanged.
- Remove the old paint!
Use wet sand paper with different granulations for the individual sanding phases. Start with a granulation of P400, then P600 and 800 or 1000 in the end. You can remove the paint chemically as well or blast. But remember to remove the sanding dust completely as soon as work is completed and wear a dust mask during the whole process.
- Clean the alloy rim’s surface!
For this purpose customary silicone remover or cellulose thinner can be used. Both are suitable for cleaning an alloy rim.
- Prime the alloy rim!
Prime the alloy rim with a filler. These are often simply called “alloy primers”.
- Apply first paint and then clear paint on the alloy rim!
Now coat the alloy rim with the color of your choice. Read the instructions carefully to make sure the paint is suitable for the rim. In the course of this keep the spray can or gun in constant motion to avoid ugly paint runs. Apply clear paint afterwards. Pay attention to the compatibility of the different components you have been using.
Rim coding explained easily
First the proper rim size has to be determined. To ensure that the measures are correct, a coding, which gives indication about it, is attached to the back of every rim. When in doubt, it is better to ask the advice of an expert before a rim with the wrong measures is purchased. The code consists of a combination of numbers and letters and indicates almost always the manufacturer besides the measures. The used pattern is a crucial make-or-break when determining whether the rim can be precisely fitted or not. The code consists of two parts, separated by the letter x. Here is an example for better understanding:
8½ J × 16 H2 ET15, LK 5× 110 MZ57
- 8½ = indicates the rim width in inches
- J = describes the condition of the rim flange
- x = describes the structure of the rim (in this case a one-piece drop base rim)
- 16 = indicated the diameter in inches
- H2 = in this case it means two Humps, so two humps on the inside of the rim
- ET15 = indicates the onset in millimeters
- LK = means bolt circle
- 5x = means number of bolt holes
- 110 = indicates the diameter of the holes in millimeters
- MZ57 = indicated the middle high centering (also called hub bore) in millimetres
What else to take care of when talking about rims
There is no disadvantage for cars with rusted rims during general inspection/emissions test. You will receive the corresponding operating license, if the rims have been recorded properly in the car documentation after installation and if they possess a Vehicle Type Approval. Special attention shall however be focused on the rim nuts. Those can be continued to be used on a case-by-case basis when changing from summer to winter tires, even when switched to a different material. As a rule of thumb, the nuts have to be screwed on the wheels as deep as their inner diameter is big. However it always should be 7 turns at least. When using a wheel nut with the labeling M12 (therefore 12 millimeter) it has to be 9 turns because of the incline of 1.25 millimeter. Pay attention to the fact that a not properly tightened rim or a wrongly used rim nut, which doesn’t fit, can lead to severe and expensive damages to the wheel suspension.