alloy wheels make a difference?

gambitt · 13 Jan 2007 at 02:02

Scuzi said:
I thought it was 1Kg of unsprung mass is equivalent to 7Kg of sprung mass.

That's probably correct (hence the "don't quote me on that"

)

Scuzi · 13 Jan 2007 at 09:22

PMKeates said:
It would be under-reading, as the larger rolling radius would mean that in each gear you'd be going faster, but the actual speed displayed will always be the same regardless of wheel size

Not necessarily. That would only be correct if the same profile tyres were used. The larger alloys get, the lower the lower the profile of the suitable tyre is hence in most cases giving the same rolling radius as a 14" steelie. This obviously goes out the window when you get to about 17" or bigger though.

Von Luck · 13 Jan 2007 at 09:44

gambitt said:
Alloy wheels are lighter than steel

Loads of people fall into this trap - in the vast majority of cases people upgrading from steel wheels to alloys will actually increase the unsprung mass of their car, usually because they buy cheap alloys and also increase the size of their wheels.

As an example - a common upgrade for MK4 Golf owners is to go from 15" steels
to 17" RS4 replicas.

Sadly:

15" steel = 16.7kg each
17" RS4 replica = 21.8kg each

If you're serious about saving weight you need to stick to the same wheel size as stock and buy top quality alloys. The difference can be dramatic.

18" OZ Superleggera - 18kg
18" R32 Replica - 26kg

If you're not willing to pay big money for a pukka make then you probably won't be getting a light wheel.

But lets face it, the majority buy aftermarket alloys for looks rather than perfomance.

Matt82 · 13 Jan 2007 at 10:04

bbs seem to be good at keeping the weight down.

one of my original rims weighed as much as one BBS with the tyre

The Edge · 13 Jan 2007 at 10:29

Does the weight really matter though?

In the grand scale of things any saving is going to be neglible in percentage terms so if all you want to do is save weight you'd do better to ban passengers

and it would cost you less

PMKeates · 13 Jan 2007 at 11:31

Scuzi said:
Not necessarily. That would only be correct if the same profile tyres were used. The larger alloys get, the lower the lower the profile of the suitable tyre is hence in most cases giving the same rolling radius as a 14" steelie. This obviously goes out the window when you get to about 17" or bigger though.

Of course. I was only highlighting the point that whatever size wheel you use the speedo always read the same actual speed relative to gear and engine speed, regardless of how fast you are going.

eidolon · 13 Jan 2007 at 13:49

Von Luck said:
17" RS4 replica = 21.8kg each
18" OZ Superleggera - 18kg
18" R32 Replica - 26kg

Crikey, they're all a bit heavy

Elise 111R alloy wheel weights

Front - 6.88kg
Rear - 9.50kg

Exige forged alloys

Front - 5.5kg
Rear - 7kg

chenko · 13 Jan 2007 at 23:31

Problem with alloys is mainly weight, get a decent set which are lightweight and you shouldnt notice too much difference.

TinkerBell said:
When I changed from steel's to alloy's I noticed a big difference with grip, the car seems to hit a lower max speed, but my steel's felt lighter than the alloys so that may be why it wont hit the speed it would before.

most is just placebo

regarding the grip, probably just new/different tyres or smaller sidewalls

Matt82 · 13 Jan 2007 at 23:36

The Edge said:
Does the weight really matter though?

In the grand scale of things any saving is going to be neglible in percentage terms so if all you want to do is save weight you'd do better to ban passengers and it would cost you less

unsprung weight. what car do you have? do you have access to lighter wheels?

i think its completely stupid when you see a reasonably sports orientated car with bling bling 18s on or something, the weight must kill the handlign

Bes · 14 Jan 2007 at 01:14

Went from disgusting standard 16" 20 spoke Cupra wheels to 18" OZ Superleggeras (Same RR) Noticed absolutley no difference in performance at all, and a marked increase in grip, I did also get a new set of Toyo Proxes fitted too though...

gambitt · 14 Jan 2007 at 02:55

don't know much about weight of wheels.. my Civic car came with limited edition 14" alloys which the previous owner had powder coated in black. I liked them so I'm never upgrading

faster acceleration, cheaper tyres, no need to spend money on new wheels. win win

The Edge · 14 Jan 2007 at 07:39

Matt82 said:
unsprung weight. what car do you have? do you have access to lighter wheels?

i think its completely stupid when you see a reasonably sports orientated car with bling bling 18s on or something, the weight must kill the handlign

I'm only learning, but my logic is that there must be a benefit other that saving a couple of KGs when spending all that money. The obvious one is that yes, they look better so why try and justify it with weight

?

gambitt · 14 Jan 2007 at 12:37

The Edge said:
I'm only learning, but my logic is that there must be a benefit other that saving a couple of KGs when spending all that money. The obvious one is that yes, they look better so why try and justify it with weight ?

It's down to the fact that a few kg extra on the wheels make a much bigger difference to handling than a few kg of sprung weight (in the car). Also, putting 18's on a car that designed for 14's is probably going to ruin the handling anyway due to the size (even with low profiles, 18's are massive)