Do lighter wheels really make a difference?

[beakr]

Nearly all four tyres on my Mini Cooper are knackered, and a couple of the wheels are a bit buckled so I thought I would treat myself to a new set of wheels and tyres all round.

I've noticed some wheels are a lot lighter than the standard ones I've got on at the moment, but I would be interested to know how much difference the lighter wheels make - is it worth spending more for less weight? Also bear in mind, I'll be ditching the run flats too

[Blue Meanie]

Yes they do... You have all the inertia and mass to get going, and to stop, not to mention the unsprung weight. It's a 'bit' like the effect yoy have with reards to a lightened flywheel, 'sort of'.

[sebhaque]

Am I right in saying the figure is every kilogram lost at the wheels equates to roughly 10 kilograms in the car?

I'm by no means an expert but I always related wheel weight to if you were moving a big block of wood or something. The weight of the wheels equates to the amount of force you need to exert to get the damn block moving in the first place. Less weight = less pressure, and it's exponentially linked to the amount of effort required to keep it moving (or accelerate it) when it actually moves. The lighter the block, the easier it is to heave off from a standstill, and then push harder to get more momentum.

Eh, it worked in my mind. I'm a few beers in so I'm hoping that still makes sense!

[Rollcage]

I think unsprung weight is the key, rather than the effect on the overall weight of the vehicle!

[Strawman]

Definitely, I've swapped alloys for steel wheels before and the whole car felt more leaden to drive; acceleration, turn in, braking were all affected.

[Illustrious_Len]

Strawman said:

Definitely, I've swapped alloys for steel wheels before and the whole car felt more leaden to drive; acceleration, turn in, braking were all affected.

My wife's old Mini Cooper (R50) had the 17" S-Line style alloys on, which looked great. Tried a friends' car that was identical - except it was equipped with the 16" 5 star style and it felt a lot "lighter on it's feet" as it were. The 15" ones are even nicer again - but look cack - so there's a balance to be reached.

Think of going running - it's much easier in trainers than it is mud-caked wellies. Same with unsprung weight on cars.

[Poledriver]

In simple terms, a lighter wheel will travel a shorter distance when hitting a bump so will return back to it's 'proper' position (pressing hard against the road) faster than a heavier wheel will, this will equate to giving far better grip!

[zakelwe]

Depends how light you go. Remember a lot of the mass is still in the tyre so you are not losing that actual much compared to the whole weight. As well as going lighter I suggest smaller and less width so the tyre gets lighter as well to add to it.

I did 205/40 16 8kg wheels to 195/45 15 5.3kg wheels and didn't notice much to be honest. Very subjective...

Andy

[Rollcage]

If you have a car where a choice of steel or alloy wheels is available from the factory, I would wager you wont notice a blind bit of difference - something on 15's or 16's in a normal width it will be very difficult to tell the difference - the difference in weight is only a couple of pounds. Obviously, go up wheel/tyre sizes and the proportionate difference is greater.

It is also not true to say that all alloy wheels are lighter than the equivalent steel option - a lot has to do with the design of the alloy.


For really significant weight differences you need forged alloy wheels, as opposed to cast.

Some early Carlton GSIs had a forged alloy on them, and some had the same design ,but cast. the difference in weight was very noticeable, but for cost reasons they didnt appear on many cars.

[HereBeMonsters]

I recently changed my French made SMR wheels for the proper Italian Speedlines, and I can definitely tell the difference. Can't remember how much each wheel weighs, but they're noticably lighter.

[Rollcage]

Poledriver said:

In simple terms, a lighter wheel will travel a shorter distance when hitting a bump so will return back to it's 'proper' position (pressing hard against the road) faster than a heavier wheel will, this will equate to giving far better grip!

I dont think it makes it travel a shorter distance, Poley - if anything,it will be further?

A lighter wheel move more easily to follow the road surface - it has a less inertia to overcome and accelerates more quickly on compression and rebound, as you say. If it accelerates faster, it will cover more distance in a given time.

I may be, and am quite prepared to be, wrong though!

[Illustrious_Len]

Rollcage said:

Poledriver said:

In simple terms, a lighter wheel will travel a shorter distance when hitting a bump so will return back to it's 'proper' position (pressing hard against the road) faster than a heavier wheel will, this will equate to giving far better grip!

I dont think it makes it travel a shorter distance, Poley - if anything,it will be further?

A lighter wheel move more easily to follow the road surface - it has a less inertia to overcome and accelerates more quickly on compression and rebound, as you say. If it accelerates faster, it will cover more distance in a given time.

I may be, and am quite prepared to be, wrong though!

Surely less mass will give the damper less work to do, meaning the damping response occurs quicker, meaning the chassis is less unsettled for a shorter time.

/not an engineer

[B'stard Child]

Rollcage said:

are lighter than the equivalent steel option - a lot has to do with the design of the alloy.

For really significant weight differences you need forged alloy wheels, as opposed to cast.

Some early Carlton GSIs had a forged alloy on them, and some had the same design ,but cast. the difference in weight was very noticeable, but for cost reasons they didnt appear on many cars.

My favorite subject - all the carlton GSi's fitted with the slabby 5 spoke wheels were forged alloys however there were two versions and one is heavier but not by much - later 10 spokes were cast and a lot heavier

Incidently the 15' steel wheels were lighter than even the 5 spoke forged alloys

[Rollcage]

B'stard Child said:

Rollcage said:

are lighter than the equivalent steel option - a lot has to do with the design of the alloy.

For really significant weight differences you need forged alloy wheels, as opposed to cast.

Some early Carlton GSIs had a forged alloy on them, and some had the same design ,but cast. the difference in weight was very noticeable, but for cost reasons they didnt appear on many cars.

My favorite subject - all the carlton GSi's fitted with the slabby 5 spoke wheels were forged alloys however there were two versions and one is heavier but not by much - later 10 spokes were cast and a lot heavier

Incidently the 15' steel wheels were lighter than even the 5 spoke forged alloys

I knew it was something like that - my Monza/Carlton/Senator/Manta days are sadly behind me!

Unlike some on here!

[Poledriver]

Rollcage said:

Poledriver said:

In simple terms, a lighter wheel will travel a shorter distance when hitting a bump so will return back to it's 'proper' position (pressing hard against the road) faster than a heavier wheel will, this will equate to giving far better grip!

I dont think it makes it travel a shorter distance, Poley - if anything,it will be further?

A lighter wheel move more easily to follow the road surface - it has a less inertia to overcome and accelerates more quickly on compression and rebound, as you say. If it accelerates faster, it will cover more distance in a given time.

I may be, and am quite prepared to be, wrong though!

Being lighter the wheel will move faster so reacting to a 'bump' earlier. Also the spring effect will occur sooner so forcing the wheel back down sooner. Maybe I would have been more correct to have quoted a shorter time rather than a shorter distance!

[Rollcage]

Illustrious_Len said:

Rollcage said:

Poledriver said:

In simple terms, a lighter wheel will travel a shorter distance when hitting a bump so will return back to it's 'proper' position (pressing hard against the road) faster than a heavier wheel will, this will equate to giving far better grip!

I dont think it makes it travel a shorter distance, Poley - if anything,it will be further?

A lighter wheel move more easily to follow the road surface - it has a less inertia to overcome and accelerates more quickly on compression and rebound, as you say. If it accelerates faster, it will cover more distance in a given time.

I may be, and am quite prepared to be, wrong though!

Surely less mass will give the damper less work to do, meaning the damping response occurs quicker, meaning the chassis is less unsettled for a shorter time.

/not an engineer

I dont know enough to express myself too eloquently, but I cant see how a lower unsprung weight would lead to the wheel travelling a shorter distance.It will do what it needs to do - its the speed it can do it at that is important, not the distance it covers - you cant really control that, as it is dependent on the road surface.

I dont disagree with the rest of Poley's post, nor yours.

Suspension design is pretty complex - I'm getting a headache now!

[Rollcage]

Poledriver said:

Rollcage said:

Poledriver said:

In simple terms, a lighter wheel will travel a shorter distance when hitting a bump so will return back to it's 'proper' position (pressing hard against the road) faster than a heavier wheel will, this will equate to giving far better grip!

I dont think it makes it travel a shorter distance, Poley - if anything,it will be further?

A lighter wheel move more easily to follow the road surface - it has a less inertia to overcome and accelerates more quickly on compression and rebound, as you say. If it accelerates faster, it will cover more distance in a given time.

I may be, and am quite prepared to be, wrong though!

Being lighter the wheel will move faster so reacting to a 'bump' earlier. Also the spring effect will occur sooner so forcing the wheel back down sooner. Maybe I would have been more correct to have quoted a shorter time rather than a shorter distance!

Thats it, we have it!

(ETA you posted your reply during the time I took to respond!)

Edited by Rollcage on Saturday 2nd January 02:20

[AUDIHenry]

zakelwe said:

Depends how light you go. Remember a lot of the mass is still in the tyre so you are not losing that actual much compared to the whole weight. As well as going lighter I suggest smaller and less width so the tyre gets lighter as well to add to it.

I did 205/40 16 8kg wheels to 195/45 15 5.3kg wheels and didn't notice much to be honest. Very subjective...

Andy

http://www.miracerros.com/mustang/ww.htm

A very important point you've just made: if you get a difference sized tire by replacing your wheel and saving weight, your net savings may be zero.

Also, filling up with helium helps.

[Accelebrate]

Illustrious_Len said:

Strawman said:

Definitely, I've swapped alloys for steel wheels before and the whole car felt more leaden to drive; acceleration, turn in, braking were all affected.

My wife's old Mini Cooper (R50) had the 17" S-Line style alloys on, which looked great. Tried a friends' car that was identical - except it was equipped with the 16" 5 star style and it felt a lot "lighter on it's feet" as it were. The 15" ones are even nicer again - but look cack - so there's a balance to be reached.

Think of going running - it's much easier in trainers than it is mud-caked wellies. Same with unsprung weight on cars.

I was given an S-Line wheel with run flat tyre by a friends dad as a spare when I got my car. I couldn't believe how heavy it was as I lifted it into the boot. It's the heaviest 17" wheel I've ever lifted, quite ironic that MINI fitted them to the quicker cars in its range for years.

[bennyboysvuk]

I had some track wheels for my E36 M3 that ran on Alpinas on the road. The Alpinas were something like 3kg a corner more than the track wheels (BBSs). The difference wasn't night and day, but it was definitely noticeable. The car just felt better all round. I think the biggest difference was on changing direction where it just seemed keener to turn.