Lightweight alloy advantage?

spaz

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I was wondering what are the advantages of alloy wheels which weigh a few kg lighter than normal ones?

Obviously overall vehicle weight will be slightly reduced but what other advantages/disadvantages do they have, I've heard they can slightly improve handling or is this a load of tosh?
 
Well normally alloys are bigger than the OEM wheels they replace so they use a lower profile tyre to keep the outside diameter the same. Lower profiles give sharper handling due to less tyre roll and normally better rubber compounds on an uprated tyre, so that's why you get your handling improvement, just at the expense of a harsher ride usually.

If the wheel is lighter it can make a difference but only noticeable on the track as 'unsprung weight'. A lighter wheel can react faster to bumps etc.
 
Faster acceleration, better braking and less unsprung weight

and...

...lower likelyhood of back injury when removing that 'phat' 20" chrome alloy from your hubs :)
 
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thought there was a rolling mass claculation where x amount of kg saved per wheel would make x amount of difference to accelleration (small % but a % non the less) etc?
 
a lot of alloy wheels are barely any lighter than their steel equivalents.
Most alloy wheels are styled to look nice, and steel wheels are designed to be strong, light and not use too much steel.
 
penski said:
Steels are usually lighter than same-size alloy rims.

*n
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Quoted for the truth

However thats usually because alloys are wider as well so greater in size. You can get lightweight alloys such as the Oz Super/Ultraleggera range. My 16" superleggera's weigh about 4-5kg without the tyres which is nothing.
 
Guys he didn't just ask what the advantage of alloys were, but specifically light weight ones, so doesn't matter that most style alloys are about the same weight as their steel counterparts, he's after specifiaclly lighter wheels :)

As mentioned, less unsprung mass, should improve acceleration.

Also OP doesn't mention anything about changing sizes, just having lighter wheels :)

Nice set of magnesium "alloys" should do the trick, quite pricey though I think :P
 
Ev0 said:
Guys he didn't just ask what the advantage of alloys were, but specifically light weight ones, so doesn't matter that most style alloys are about the same weight as their steel counterparts, he's after specifiaclly lighter wheels :)

As mentioned, less unsprung mass, should improve acceleration.

Also OP doesn't mention anything about changing sizes, just having lighter wheels :)

Nice set of magnesium "alloys" should do the trick, quite pricey though I think :P
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I got the impression the OP was assuming that alloys weigh less than steelies, which i think most people assume. just making sure he knew.
 
Isn't there something to do with less weight = less gyroscopic force = sharper turn in and 'more feel'?

I'm not claiming this to be true, I just recall reading it somewhere.
 
A good sorted list of wheel names, casting method, dimensions and weight in lbs

http://zombiehunters.org/events/wheels2.pdf


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Compared to stock wheels for a Pulsar you saved 7x4, 28 pounds (13kg) in unsprung weight aprox using those wheels if that chart matches up right
 
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My speedline Turinis around half as light than my std vtr alloys, but still a little heavier than the spare steel wheel.
 
Ev0 said:
Guys he didn't just ask what the advantage of alloys were, but specifically light weight ones, so doesn't matter that most style alloys are about the same weight as their steel counterparts, he's after specifiaclly lighter wheels :)

As mentioned, less unsprung mass, should improve acceleration.

Also OP doesn't mention anything about changing sizes, just having lighter wheels :)

Nice set of magnesium "alloys" should do the trick, quite pricey though I think :P
Click to expand...

Indeed, I maybe worded it a little badly, but meant the advantages of lightweight alloys over regular ones.

Was thinking about getting some for my car, but I reckon the money will be better spent on better springs and various power increasing items for the time being.
 
Reducing the mass of a rotating part gives a more noticable effect to acceleration than removing the same amount of weight from a non rotating part e.g. saving 10kg by changing wheels will have a greater effect on acceleration than removing 10kg of weight from the interior.

Better handling and ride comfort is also an advantage you get when reducing any unsprung weight. You probably won't notice much difference though :)
 
By what factor does it affect acceleration though, obviously it reduces the overall PWR so is it 4 times more effective ?
13kg then being equalivant to 52kg lost from the overall weight?


edit:

wiki kicked this up - http://en.wikipedia.org/wiki/Unsprung_weight

What you need to know is that changing to tires that are 1 lb heavier will effectively add 8 lbs to the car (four tires, remember) and that adding a pound to the wheels will effectively add somewhere around 6 lbs to the car.
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http://www.sportcompactcarweb.com/editors/technobabble/0109scc_technobabble/
 
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GT3 said:
My speedline Turinis around half as light than my std vtr alloys, but still a little heavier than the spare steel wheel.
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Yeah Turinis aren't too bad, approx 7.5 kilos for a 15, 8.4 kilos for a 16, 8.7 kilos for a 17 :)
 
"1Kg removed in unsprung weight is worth 8Kg removed in sprung weight."

I think that's the correct saying...

Anyhoo...You're looking at around 8Kg for a 7x15 steel wheel...Suddenly your Superleggaras look a bit portly...

*n
 
If the above chart is right then a superleggra 15x7 is 11lbs or 5kg per wheel and its only the tyre which is twice as important in its weight as sprung weight since its on outside of the rotation, the wheel is just 1.5x (since the centre mass barely produces any extra inertia)

I've never really heard of lightweight tyres, I guess low profile does the job there
 
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