Why do car manufacturers use alloy wheels?

[230K]

Hi

Why do car manufacturers use alloy wheels, it doesnt seem to be for weight reduction as my 16" steel spare is 19kg

My 17" winter alloy wheels are 21kgs!! 235/45/17

And my 18" AMG alloys are 23kg regardless whether they are front or back of the staggered set up 235 & 265 wide.

Would a plain steel wheel be lighter???????

230K

 

[Bobby Dazzler]

Because they look nice, and people buy them for that reason, enabling the manufacturer to charge a premium.

Wider wheels are unecessary by and large, and like heavier wheels can also have a negative affect on the way the car behave.

 

[jaymanek]

Alloy wheels are cheaper to manufactuer in large quantities

 

[pauldmaynard]

Because they look great in the showroom but after 2 or 3 years they look crap so you buy a new car

 

[Number_Cruncher]

Yes, most standard fit alloy wheels are a triumph of slick marketing over good engineering. Steel is much more damage tolerant and robust in this application.

However, the worst offender for this prize, in my opinion, goes to the fitment of rear disc brakes on front wheel drive shopping trolleys. On the rear axle of a MB estate, fair enough, because,

a) there's a large rear overhang, and so, there's a reasonable amount of weight at the back

b) there's the rear wheel drive apparatus putting more weight over the back wheels

c) MB tend to do a proper job of fitting a decent handbrake by using small shoes within the well of the disc rather than bodging and trying to use the caliper

On most FWD shopping trolleys, there's no weight over the back to start with, and duirng braking, owing to weight ransfer, there's even less, so, drum brakes are more than adequate, and are easy to implement a handbrake with.

Sorry about the thread creep away from useless alloy wheels..., but, it's all similar nonsense to me.

There is only any significant improvement in ride and handling if the unsprung mass is reduced during design, and the spring and damper rates chosen to complement this. Reducing mass later just results in an overdamped suspension.

 

[Shude]

When I had the tyres changed on my 16" rims I was amazed at how light a wheel was without the tyre! I'm certain that a lot of the weight is down to the tyre.

Tried weighing the tyres?

 

[Dryce]

However, the worst offender for this prize, in my opinion, goes to the fitment of rear disc brakes on front wheel drive shopping trolleys. On the rear axle of a MB estate, fair enough, because,

My first bike had a drum at the rear. When I got my next one it had a disc.

Injudicious use of the brake pedal would lock up either easily. Still preferred the disc on the rear - it seemed to have more 'bite' and better feel.

 

[pauldmaynard]

Yes, most standard fit alloy wheels are a triumph of slick marketing over good engineering. Steel is much more damage tolerant and robust in this application.

However, the worst offender for this prize, in my opinion, goes to the fitment of rear disc brakes on front wheel drive shopping trolleys. On the rear axle of a MB estate, fair enough, because,

a) there's a large rear overhang, and so, there's a reasonable amount of weight at the back

b) there's the rear wheel drive apparatus putting more weight over the back wheels

c) MB tend to do a proper job of fitting a decent handbrake by using small shoes within the well of the disc rather than bodging and trying to use the caliper

On most FWD shopping trolleys, there's no weight over the back to start with, and duirng braking, owing to weight ransfer, there's even less, so, drum brakes are more than adequate, and are easy to implement a handbrake with.

Sorry about the thread creep away from useless alloy wheels..., but, it's all similar nonsense to me.

There is only any significant improvement in ride and handling if the unsprung mass is reduced during design, and the spring and damper rates chosen to complement this. Reducing mass later just results in an overdamped suspension.

With rear disc the ABS works beter

 

[230K]

When I had the tyres changed on my 16" rims I was amazed at how light a wheel was without the tyre! I'm certain that a lot of the weight is down to the tyre.

Tried weighing the tyres?

The interesting thing was that the 18"x8" wheel with 235/40/18 tyre weighed the same as the 18"x9" with a 265/35/18 tyre. Both were 23kgs!!

230K

 

[Number_Cruncher]

>>With rear disc the ABS works beter

Yes, it was true at one point that ABS couldn't work at all with rear drums because of their different threshold pressures, and larger free travel, but, I think that the more modern ABS controllers can, largely, overcome this.

 

[popuptoaster]

Its mainly down to what customers want and will pay extra for, but proper alloy wheels transfer heat away from the brakes better and are much lighter, trouble is proper ones with a high magnesium content corrode a lot faster so only get used in racing applications, racing tyres are also lighter than road tyres, larger alloy wheels are usually worse for handling because of the increase in unsprung weight, but an increase in rolling radius gives a larger tyre footprint so on smooth circuit racing cars they use large wheels, while rally cars tend to use smaller wheels as the suspension has to work harder.

 

[Uberwagon]

I thought the ABS issue on rear drums was due toi the self servoing action of a drum brake, due to the leading edgs?

Dave!

 

[flango]

I had a FWD shopping trolley, a Volvo V70 T5 would I want drum brakes on the back of it, would I hell!!!! Just look at the laws of physics & Dynamics. Disc brakes flat surfaces coming together to decrease velocity, drum brakes curved surfaces coming together to decrease velocity. Go figure which is the most efficient, I think and 11 year old in a physics class could work that one out wouldn't even make it to a GCSE paper.

 

[bolide]

With rear disc the ABS works beter

Why?

Nick Froome
www.w14.co.uk

 

[stats007]

Forged alloy wheels are considerably lighter, as are magnesium. Tyre weights vary by brand up to 2kgs each in some cases (18").

 

[Doodle]

Forged alloy wheels are considerably lighter, as are magnesium.

They're also eyebleedingly expensive - the forged wheels on the Civic are around 6kg for an 8.5x18, and about £400 a corner even at trade price

 

[stats007]

I suppose it's all relative but I'd expect to pay £500 for a new wheel anyway.

 

[Doodle]

For an OEM wheel, certainly. The wheels in question are aftermarket, but definitely at the top of the tree.

Does make you wonder how much markup they're making when a heavy cast wheel costs just as much?