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Discussion Starter · #1 ·
After changing the wheels I noticed all the posts on here about weight of REP wheels

The monty IIs were lighter than my REP RS4 rims & tyres.

But how does this really effect the car. MPG is down ok

Weight causes problems with handling,under steer ??

Should I be worried or even removing them. I didnt want to pay loads for the wheels because I might upgrade the car next year .

Many thanks
 

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There's all sorts of factors to consider with weight in wheels - unsprung weight, rotational mass etc etc.

Basically extra weight is a bad thing in most instances, the shocks need to work harder to control the extra mass, the bushes will wear faster due to the extra stress, the engine needs to work harder to get them spinning, the brakes need to work harder to slow them down and so on......

If you're buying for cosmetic purposes then performance is not an issue and you'll be fine. If buying for performance then make sure you buy lightweight race/rally spec wheels which will be lighter and stronger than std ones. Obviously cost is a factor there, so it comes down to how much do you really want the wheels?
 

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Weight causes problems with handling,under steer ??
As Richard already said about dampers having to work harder to control them. Also the way the mass is distributed makes a difference. The larger the wheel, and the more mass it has towards the edge of the rim, away from the centre, the more pronounced the gyroscopic effect - which corrupts steering feel. If you gently tilt a spinning computer hard disk (3.5" size, not laptop or smaller) from side to side, you'll know what I'm talking about. Also, the larger the wheel, the more important that it's as strong as possible, purely from a safety point of view. Over the lifetime of a wheel it has to endure millions of load changes as you steer the car and it travels across uneven surfaces, so once again, a lightweight wheel made of high quality alloy is worth the extra money as the metal will not fatigue so easily.

Chassis balance is more to do with suspension geometry and tuning, and the state of your tyres.

As for your Monty IIs, I'm guessing your RS4 reps were at least 17" if not 18", the most common, so they'd be at an immediate disadvantage even if made of the same stuff as the Monty IIs.
 

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Discussion Starter · #4 ·
Weight causes problems with handling,under steer ??
As Richard already said about dampers having to work harder to control them. Also the way the mass is distributed makes a difference. The larger the wheel, and the more mass it has towards the edge of the rim, away from the centre, the more pronounced the gyroscopic effect - which corrupts steering feel. If you gently tilt a spinning computer hard disk (3.5" size, not laptop or smaller) from side to side, you'll know what I'm talking about. Also, the larger the wheel, the more important that it's as strong as possible, purely from a safety point of view. Over the lifetime of a wheel it has to endure millions of load changes as you steer the car and it travels across uneven surfaces, so once again, a lightweight wheel made of high quality alloy is worth the extra money as the metal will not fatigue so easily.

Chassis balance is more to do with suspension geometry and tuning, and the state of your tyres.

As for your Monty IIs, I'm guessing your RS4 reps were at least 17" if not 18", the most common, so they'd be at an immediate disadvantage even if made of the same stuff as the Monty IIs.
Yes they our 18" RS4.

I have noticed a lack of low-mid range compared to the old Monty II rims. Also feel the MPG has gone down alittle.

So if you brought a set of rims from VW when buying a new golf you would have the same problem

I take it this would effect all cars, bmw etc which come with 18" as standard.
 

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With a manufacturer such as BMW you'd be suprised how much they focus on things like unsprung weight and make their OEM wheels accordingly. Putting 18" reps on a 3 series instead of OEM makes a substantial difference to ride and handling.

That's why some of the 18" and 19" BMW OEM wheels cost so much and still go for ?loads on ebay!

I haven't checked the other threads but I'll bet that OEM RS4s off a TT for example are lighter than reps.
 

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Discussion Starter · #6 ·
With a manufacturer such as BMW you'd be suprised how much they focus on things like unsprung weight and make their OEM wheels accordingly. Putting 18" reps on a 3 series instead of OEM makes a substantial difference to ride and handling.

That's why some of the 18" and 19" BMW OEM wheels cost so much and still go for ?loads on ebay!

I haven't checked the other threads but I'll bet that OEM RS4s off a TT for example are lighter than reps.
thanks for the replies

So basically adding reps is a bad thing unless you dont care and just want the look.

Unsprung weight is ?
 

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I'd like to be able to explain all about unsprung weight, but someone else has done it in a way far better than I ever could - have a look here and much will become clearer!![:D]

http://www.chris-longhurst.com/carbibles/

Yes, reps are fine in most situations, if you're aware of the disadvantages and are prepared to live with them, then there's absolutley nothing wrong. After all the extra cost is marginal and the difference in ride and handling is noticeable but not devastating.
 

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OEM wheels tend to be made by the likes of BBS (Monty II, Anni...), OZ (R32 Aristos), Ronal... Companies with a track record in racing, so know how to produce a strong, light wheel.

Unsprung weight is everything attached to the lower end of a car spring - wheels, tyres, hubs, brake discs and calipers, suspension control arms. None of these are supported by the spring - everything attached to the upper end of a spring is sprung weight. Unsprung weight is what flaps up and down at a very fast rate as you drive, and less of it is better.
 

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I'd like to be able to explain all about unsprung weight, but someone else has done it in a way far better than I ever could - have a look here and much will become clearer!![:D]

http://www.chris-longhurst.com/carbibles/
That's more than I ever want to know about suspension [:|]

Aiiieeee, read about that Bose LEM stuff before, very swish! [H] Brings a new meaning to, "I've got Bose in my car..."
 

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Unsprung weight is everything attached to the lower end of a car spring - wheels, tyres, hubs, brake discs and calipers, suspension control arms. None of these are supported by the spring - everything attached to the upper end of a spring is sprung weight. Unsprung weight is what flaps up and down at a very fast rate as you drive, and less of it is better.
That's a nice way of explaining it.

As I've said before, I've got an issue with fitting bigger (and maybe heavier) wheels to my car that look good but actually blunt the performance. That and the cost of course. [:)] IMO that's the trouble with some of these mods. They make the car look so much better and at times can give the impression of improved performance but can actually make it worse. For example, I fitted Eibach springs a few weeks ago and prefer how the car looks now. The ride is also very good but I've noticed an increase in bump steer so that I'm having to make fiddly adjustments to the steering at motorway speeds. I reckon my car goes round bends a bit better but the steering seems noticeably worse, if that make sense.[:^)]
 

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Discussion Starter · #11 ·
So will all 18 " rims have this problem.

The anni has 18" rims but I take it because there BBS they will be lighter and not have these problems.

I put the old rims back on today and did notice the weight difference alright.

The RS4 rims were much harder to lift off and on the hubs.

The drive felt different as well, the low - mid range felt better again.

What options have I got to installing 18" rims without these problems ?
 

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The answer is... not cheap. Forged rims are the lightest and strongest. Most alloys are cast, which is cheaper but heavier and not as strong.
 

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Discussion Starter · #13 ·
The answer is... not cheap. Forged rims are the lightest and strongest. Most alloys are cast, which is cheaper but heavier and not as strong.
Hmm

What about R32 wheels

Would these be lighter
 

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The answer is... not cheap. Forged rims are the lightest and strongest. Most alloys are cast, which is cheaper but heavier and not as strong.
Yep, loads of dosh. Well loads as far as I'm concerned.
 

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Discussion Starter · #15 ·
This is crazy

Everyone on here who brought rep rs4 wheels has the same problems? and what

dont care? or dont know about this.

Has anyone else felt a drop in MPG or power?

On a plus point it doesnt handle nice on round abouts.

I put the old set of monty IIs on today and it felt different. The brakes even felt better

Its strange how an extra 4kg per wheel is doing this
 

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This is crazy

Everyone on here who brought rep rs4 wheels has the same problems? and what
Yep, I suffer from it with RS4 reps.

Tempted to put the Avus II's back on even go down the steelies route.

Have been looking at ATS DTM's, they are a lighrweight wheel that look very similar to the R32 rims for reasonable money to.
 

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Discussion Starter · #17 ·
This is crazy

Everyone on here who brought rep rs4 wheels has the same problems? and what
Yep, I suffer from it with RS4 reps.

Tempted to put the Avus II's back on even go down the steelies route.

Have been looking at ATS DTM's, they are a lighrweight wheel that look very similar to the R32 rims for reasonable money to.
What stuff do you suffer from?

Have you got a link for these ATS rims as well please
 

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Discussion Starter · #18 ·
This is crazy

Everyone on here who brought rep rs4 wheels has the same problems? and what
Yep, I suffer from it with RS4 reps.

Tempted to put the Avus II's back on even go down the steelies route.

Have been looking at ATS DTM's, they are a lighrweight wheel that look very similar to the R32 rims for reasonable money to.
What stuff do you suffer from?

Have you got a link for these ATS rims as well please
 

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I'm staying with my 16" Monty rims for now.  The only 18" rim that I've found that seems to offer a reasonable compromise between looks, weight and price is (wait for it) the BBS RC.  It's not my favourite in terms of looks but seems to be lighter than a good many others around.
 
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