A common dilemma - Help required...

[MugelloR]

Really? I thought the point would be that they are light! I know I'm in the minority but I don't really like them and I had assumed they were bought primarily for weight saving.

Weight saving!!! Not sure that would be a pre requisite on a car weighing in the region of 2 tons??

[Fen]

It's always worth saving unsprung weight.

[MugelloR]

It's always worth saving unsprung weight.

Not sure where this is heading.......but nevertheless I'm certain MTM had it covered in their engineering calculations and design criteria...

[Fen]

It's not heading anywhere from my perspective - I had assumed they would be lighter than then OE wheels and someone said they are heavy which surprised me (are the OE ones heavier still?), then you questioned the need to save weight on a 2 tonne car and I said unsprung weight is always worth saving. Imagine running with weights round you ankles - it's not the same thing but it gives an idea.

[MugelloR]

There are many arguments for and against the unsprung weight issue on todays and infact yesteryears cars.....here's one of the more credible.

"The unsprung weight of a wheel controls a trade-off between a wheel's bump following ability and its vibration isolation. Bumps and surface imperfections in the road cause tyre compression which induces a force on the unsprung weight. Accordingly, the unsprung weight then responds to this force with an independent movement of its own. The amount of movement is inversely proportional to the weight, a lighter wheel which readily moves in response to road bumps will have more grip when tracking over an imperfect road. For this reason lighter wheels are often specified for high performance applications ie racing. In contrast, a heavier wheel which moves less will not absorb as much vibration, therefore the irregularities of the road surface will transfer to the cabin through the geometry of the suspension and hence ride quality paradoxically deteriorates.

Though this is usually not considered important, there is however a positive effect: High frequency road irregularities, such as the gravel in an asphalt or concrete road surface are isolated from the body more completely because the tires and springs act as separate filter stages and damping mediums, with the unsprung weight tending to uncouple them.

Heavier wheels are definitely more stable and therefore impart a more comfortable ride and in practical terms of day to day driving, one may infact be unable to notice any real difference."

However, one must consider PSS9 and other coil over shod vehicles in a different light given that the bump and rebound characteristics are infinitely tuneable by design.

Being that the weight differential between the OEM 5 spokes and the Bimotos is of such minor insignificance to the overall influence on the running gear and ride geometry it is my considered opinion that one would never be able to notice the difference, and in my opinion the MTM's look nicer too!!! To each their own.....

[Fen]

To each their own is absolutely right - I really just expressed surprise that the MTMs are not consiedrably lighter than then OE wheels.

It wasn't ans still isn't my intention to have an argument but because I don't want someone reading the forum to be misinformed I have to say that the bit you quoted about heavier wheels imparting a more comfortable ride is utter nonsense.

[MugelloR]

Far be it that I am after an argument but considering that you have now uttered the phrase utter nonsense can you justify / qualify that????

[Rich_C]

Dave,

I'm not sure if you've made your mind up yet but here's a few things to consider mainly because I went through the same soul searching regarding alloys.

If your damaged alloy just needs a refurb it's going to cost you £100'ish to have it done plus the one on the same side so you don't get an obvious colour difference.

If it needs replacing your going to have to either find a used replacement (£200'ish) or buy one new (£500'ish).

If your heart is set on aftermarket replacements then my personal preferences are either sportec or MTM but this route isn't cheap (£2500'ish) especially as your going to need to fit new tyres. If you've had your monies worth out of your current tyres then this isn't too bad. The question you then need to answer is what are you going to do with your old OEM alloys - if you plan to sell to offset your new purchase chances are you'll need to get them refurbed in order to get top price.

Personally until seeing the MTM's in the flesh I thought they looked quite plain in pictures and too similar to the style of the OEM 18" 9 arm alloys that were a no cost option. At this time I really fancied a set of 20" Sportec Mono's - although I was a little concerned with the extra 1" of clearance. However, after seeing a set fitted to an S4 I felt a little underwhelmed by them (maybe my expectations were too high?) where as after seeing the MTM I had the "must buy now" impulse/desire. The MTM's are far more 3-dimensional in the flesh and I can guarantee the titanium inserts will look awesome against the daytona paintwork. I deliberately stayed away from a full anthracite coloured wheel as I personally thought it would look too much against the grey paintwork and would detract from the overall look of the car - just my opinion.

As for unsprung weight - in all honesty it didn't cross my mind when I bought them and doesn't concern me now. If they had been lighter then it would have been a brucey bonus but if heavier means stronger and less likely to buckle then if I had the option I would specifically choose the latter. After paying for 4 I certainly don't want to pay for a 5th in a hurry.

Rich.

[Fen]

Far be it that I am after an argument but considering that you have now uttered the phrase utter nonsense can you justify / qualify that????

Think about it - there is absolutely no sense in trying to claim that unsprung weight is a good thing. As I understand what you quoted (which came from where?) it was trying to say that on mildly uneven surfaces such as gravel the mass of the unsprung weight would resist deflection making the ride smoother. OK, that might be the case, but what happens when the unevenness gets to the point where the mass moves? The suspension has a far bigger job to stop the mass moving than it would with less mass, all the while in the likelihood that the wheel has crested whatever undulation sent it upward and is now no longer in contact with the road. Add to that the fact that heavier wheels blunt acceleration and it's a bad thing. Even if in a very specific circumstance heavy wheels help the vast majority of other real-world situations when they don't outweigh that advantage ovewhelmingly.

To be honest I am astounded that anyone is trying to say any different - you might as well tell me that the world is flat as try to convince me unsprung weight is good.

[dace]

Far be it that I am after an argument but considering that you have now uttered the phrase utter nonsense can you justify / qualify that????

Think about it - there is absolutely no sense in trying to claim that unsprung weight is a good thing. As I understand what you quoted (which came from where?) it was trying to say that on mildly uneven surfaces such as gravel the mass of the unsprung weight would resist deflection making the ride smoother. OK, that might be the case, but what happens when the unevenness gets to the point where the mass moves? The suspension has a far bigger job to stop the mass moving than it would with less mass, all the while in the likelihood that the wheel has crested whatever undulation sent it upward and is now no longer in contact with the road. Add to that the fact that heavier wheels blunt acceleration and it's a bad thing. Even if in a very specific circumstance heavy wheels help the vast majority of other real-world situations when they don't outweigh that advantage ovewhelmingly.

To be honest I am astounded that anyone is trying to say any different - you might as well tell me that the world is flat as try to convince me unsprung weight is good.

I too have a set of 19" bimoto's and agree they are heavier. In terms of handling and straight line speed there is very little difference.

It took me a while to adjust to the new wheels, however I really like them. I recently did Vmax and found no difference, compared to my lighter oem 18" 9 spokes.

[noggyblueboy]

got to be the bimotos

or what about mega wide bbs split rims?

[Fen]

I'm liking your second suggestion

[iR8V10]

Thanks for all the advice guys, certainly words from the wise. 61% for the Bimotos at present, they certainly are a Marmite wheel aren't they! Didn't think it would cause so much 'debate' but it's all healthy eh!

I think you're dead right about the RS4 wheels not being exclusive enough too, I saw them on a Citroen Saxo yesterday and it's killed them for me.

The beasty is going into Brighton Audi next week to have a few 'niggles' looked at and depending on how much I get through on the warranty depends on how much £££ I'll be left to play with.

I'm really liking the idea of the Milltek and refurbed alloys which may turn out for the best as the exhaust could be the cause of one of my niggles. Two birds, one stone!

[MugelloR]

Good luck Dave, sounds like a plan.

Thank heavens for opinions.......

[marmite]

WHAT A READ!!!!
I have also been thinking about new alloys, MTM's, ABT 20 Inch or stay standard??

Just missed auction for the 20's, but pleased as the ride would have been alot harder then it is and my wife would be more likly to kerb them. MTM's are great but I decided to stay with OEM and finish them in Plus colour