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Alloy wheels...

Community Veteran
Posts: 7,154
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Registered: 30-08-2007

Alloy wheels...

I've been told twice from different sources recently, that most alloy wheels for cars are actually cheaper to produce than steel wheels, which have a multi-stage pressing,welding, painting process + hubcaps, whereas alloy's are pretty well finished after moulding, and the material is cheaper too. So why then are steel wheels fitted to the cheaper end of a cars model range? surely under these circumstances steel wheels should be fitted to the top-of-range, and those of us who tend to buy at the cheaper end should get the better looking alloys!
This doesn't include very expensive Magnesium and titanium and other specialist wheels of course.
Experience; is something you gain, just after you needed it most.

When faced with two choices, simply toss a coin. It works not because it settles the question for you. But because in that brief moment while the coin is in the air. You suddenly know what you are hoping for.
13 REPLIES
geewizz
Grafter
Posts: 1,125
Registered: 01-08-2007

Re: Alloy wheels...

Steel wheels are alloy wheels. Steel is an alloy of iron and carbon.
Community Veteran
Posts: 7,154
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Registered: 30-08-2007

Re: Alloy wheels...

(yawn!) I do believe geewizz, that with respect, you might just have let the point escape you...
cp:quote
Experience; is something you gain, just after you needed it most.

When faced with two choices, simply toss a coin. It works not because it settles the question for you. But because in that brief moment while the coin is in the air. You suddenly know what you are hoping for.
geewizz
Grafter
Posts: 1,125
Registered: 01-08-2007

Re: Alloy wheels...

Or perhaps I need to elaborate on the point so that it is easier to understand.
My point is that the original poster is asking why alloy wheels are more expensive than alloy wheels. He then goes on to explain that one alloy wheel is easier and less expensive to produce than the other alloy wheel ... apparently.
[Moderator's note by Jonathan (chillypenguin):  Full quote of preceding post removed, as per Forum Rules ]

Note : Allow me to provide a little bit of clarity for those of us who can't see what the moderators can see.
There was a post deleted which WAS reply#3. This was only deleted AFTER what was reply#6 (now reply#5)
The timeline and edits don't make sense without that information, chillypenguin.
Community Veteran
Posts: 7,154
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Registered: 30-08-2007

Re: Alloy wheels...

May I ask Chilly penguin please to be even handed when applying the rules, see previous post.
Experience; is something you gain, just after you needed it most.

When faced with two choices, simply toss a coin. It works not because it settles the question for you. But because in that brief moment while the coin is in the air. You suddenly know what you are hoping for.
geewizz
Grafter
Posts: 1,125
Registered: 01-08-2007

Re: Alloy wheels...

In response to Reply#5,
Reply#4 quotes reply#2, not the preceding post.
alanb
Grafter
Posts: 459
Registered: 24-05-2007

Re: Alloy wheels...


I suspect the answer is lies buried in your question Petlew.
If steelies really were more expensive, then cars at the cheaper end of the range would have alloys fitted as standard. The cheap cars would just have cheap and nasty alloys, while the expensive cars would have posher more expensive alloys.
Car makers do anything and everything to shave pennies off the cost of manufacturing components, so it's unlikely they'd fit steel wheels if they could save money by fitting alloys.
I'm not sure that I'd agree with the comment on the price of aluminium alloy either. Compared with steel, aluminium is quite expensive to produce as it requires a great deal of energy. I don't know what the current prices are, but in the 1970's when I worked in the engineering sector, mild steel sheet was about 25 pence a kilo, the cheapest aluminium alloys cost several times the price of steel. Both would obviously be more expensive these days, but I would be surprised if there has been any reduction if the difference between the prices.
I'm also unconvinced that the manufacturing complexity of steel wheels is that different to alloy wheels. The moulds for injection casting aluminium are complicated and very expensive to make, more expensive than the (also expensive) press tools for a typical steel wheel, I'd say. Alloy wheels will require some machining, to remove artifacts from the moulding process, and also because molten aluminium abrades the moulds when it is injected, causing variations in the castings over time. They may also require machining for cosmetic purposes, and they need to be polished and then lacquered or painted or powder-coated to prevent corrosion.
VileReynard
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Re: Alloy wheels...

What's the point in alloy wheels if they are liable to corrosion  Smiley
Doesn't Aluminium form a thin tightly bound oxide which prevents further corrosion?

Community Veteran
Posts: 7,154
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Registered: 30-08-2007

Re: Alloy wheels...

@alamb. Well, I'm not suggesting my information is the gospel truth, I only referred to it, indeed you make a far better case for the opposite view. But my information in one case came from a very casual acquaintance with a fairly long time ex-employee of Ford (at least thats what he said he was)
Experience; is something you gain, just after you needed it most.

When faced with two choices, simply toss a coin. It works not because it settles the question for you. But because in that brief moment while the coin is in the air. You suddenly know what you are hoping for.
pierre_pierre
Grafter
Posts: 19,757
Registered: 30-07-2007

Re: Alloy wheels...

the Alloy wheels are not just Aluminium, there are  magnesium alloy and cheap Chrome/ally (from China) and the cost is doubted in this article
http://en.wikipedia.org/wiki/Alloy_wheel
Community Veteran
Posts: 4,729
Registered: 04-04-2007

Re: Alloy wheels...

Quote from: Petlew
May I ask Chilly penguin please to be even handed when applying the rules, see previous post.

May I ask you, to check the time line of the posts and edits  Wink
alanb
Grafter
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Registered: 24-05-2007

Re: Alloy wheels...

Quote from: Petlew
@alamb. Well, I'm not suggesting my information is the gospel truth, I only referred to it

I understood that Petlew. I'm sorry if I might have given the impression that I was having a go at you (or anybody else for that matter). It wasn't what I intended.
alanb
Grafter
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Registered: 24-05-2007

Re: Alloy wheels...

Quote from: axisofevil
What's the point in alloy wheels if they are liable to corrosion  Smiley
Doesn't Aluminium form a thin tightly bound oxide which prevents further corrosion?

Yes, aluminium does.
But, Pure aluminium is too soft and ductile for making wheels.
When it is alloyed with other elements it becomes a different material with a different set of properties. Alloying reduces or destroys aluminium's corrosion resisting properties.
The point of alloy wheels (or perhaps that might also be: the point of cast or moulded wheels) is that they can be made in more intricate and attractive shapes. Also, the expensive alloy wheels fitted to high-performance cars can be made from materials that are very strong but are considerably lighter than steel.
pjemmanuel
Grafter
Posts: 349
Registered: 05-04-2007

Re: Alloy wheels...

Quote from: Petlew
whereas alloy's are pretty well finished after moulding

Unfortunately this is very untrue. Moulding/casting is quite a rough process where wheels are concerned and apart from the decorative front of the wheel, the remainder of the rim is cast oversize.
Following the casting, you have to heat treat the castings so that they gain their full strength, then age them for 24 hours.
After that, you have to machine them to their final size, which can in some cases remove kilograms of material, which you may be able to reclaim and reuse after you clean it of all the cutting oils. During the machining process, the outside profile and the inside walls are machined, to ensure that the rim profile is consistent, and as such doesn't  affect the balance of the wheel. The mounting face and mounting bore are also machined and the fixing bolt holes and inflation valve hole is drilled.
After this comes the paint coating of the wheel after lots of chemical treatments to remove all the smut and cutting oils used in the manufacturing process. At the end of it all, you get a nice shiny pretty wheel.
Now, there are some manufacturers who skimp on the machining of these wheels, they cast them close to finish size and only machine parts of the wheels, mainly the mounting face and bore and the bead seats, which is where the tyre sits and makes contact with the rim. This is all well and good, these are the main functional areas of the rim, but there is a possibility that because the whole inside and outside of the casting hasn't been machined concentrically, the wheel will be difficult to balance and you'll end up with hundreds of grams of weights on the rims.
Quote from: alanb
Alloying reduces or destroys aluminium's corrosion resisting properties.

Actually, aluminium doesn't resist corrosion, it's just that the corrosion doesn't penetrate into the material like rust does in iron.
Also, aluminium oxide is much tougher that aluminium so when aluminium oxidises, it hardens the surface layer. You can drive the oxidisation deeper into the surface using an anodizing process to make the hard oxidised surface layer much thicker than you could achieve by natural oxidisation alone.
Even an aluminium alloy wheel will develop a dull grey appearance within a few days as the surface oxidises. You wouldn't want a bare aluminium wheel on your car, within a week it would look awful.

It's also a fallacy that aluminium wheels are lighter than steel wheels. Yes, the base material is lighter, but on the whole it's not as strong so the rim profile is generally thicker. If you doubt this statement, go take a look at the wall section and decorative face thickness of and alloy wheel, then compare it to a steel wheel. Typically, you are looking at 5mm to 8mm wall thickness for alloy, with a decorative face in excess of 50mm, plus all the extra bulk at the centre of the wheel where the mounting bolts are. On a steel wheel, you are looking at 4mm to 5mm on all surfaces.
It is possible to make alloy wheels very light, with very thin wall sections, but those type of wheels only achieve their full strength when a tyre correctly inflated is added to them. Get the tyre pressure wrong, and the wheel loses a lot of it's strength.
Usually, aluminium wheels are chosen, as alanb states, simply because you can have more intricate designs and shapes than is economically possible when made out of steel.