finally picked up the RS6

[Dipper]

Looks good. Can't say i notice that much of a difference in looks. How's the 0>60 quicker? Surely the radius is the same as you'll have a larger profile tyre?

[Shoppinit]

im looking for 19 inch alloys, i like the mtm bimotos grey...
i think 19 inch look much better and fill up the wheelarches more...
0-60 is a bit quicker with 18 inch.

The MTMs are less wide.

Why is the `0-60 quicker with 18"? Better be a good explanation

[mavada]

18x255x30
19x255x30
so the 19 needs a bit more force to get them rolling because of the overall diameter...
yes ive heard the mtms are smaller, dont know why... are there similar designs with 9 width?

A larger, heavier tire and wheel assembly will gain more kinetic energy
from each short bump it encounters,
which the suspension then tries to absorb without passing on to the
passenger cabin.
So smaller tires give a smoother ride.
When tires bounce, a given amount of suspension hardware can put them back
in contact with the road quicker if they have low mass.
So smaller tires should give better handling.

The ground-contact footprint of the tire will grow or shrink until air
pressure bears almost exactly the weight of the car.
[ inflation_pressure x footprint_area x number_of_tires =
vehicle_weight ]
For a given weight you could use small tires inflated to high pressure,
or small tires at low pressure with a long, soggy footprint,
or larger tires with either pressure.
Flexing and smacking heavy rubber on the pavement every revolution uses
some energy, makes some rolling friction,
so I think that small tires at high pressure are known to be the most
fuel-efficient choice.
Large flexing of rubber at high speeds also makes heat, which makes tires
wear out or blow out sooner.

It is not always engines pushing tires. Often tires push engines back.
Smaller wheels have less angular inertia, and less torque when skidding,
so they present less threat of damaging the power-train metal parts.
This is most evident in off-roading, where huge tires sometimes break
drive shafts or axles when a tire suddenly lurches into a rock.
The axle is caught between the sudden torque on the tire, and the angular
inertia of the geared-down engine.
(The fluid clutch in an automatic transmission is a partial safety-relief
for this stress.)
But I am becoming very aware lately that when you apply gears to an
angular inertia (say of an engine),
the apparent rotary inertia goes as the _square_ of the gear ratio. That
figures in somewhere.

On the other hand, small high-pressure tires have more load per square
inch and should wear down faster,
and large low-pressure tires often have better traction in various
circumstances.

Large diameter wheels and tires effectively put the car in a slightly
higher gear,
which in principle could be compensated for by having a different set of
gears in the power train,
but in the real world that change isn't usually cost-free.
If your engine is overpowered or "torquey" with its given gear set, a
larger tire diameter helps you use that for speed.
Conversely many small engines will need small tires to do their (very
modest) best acceleration.

The rotary inertia of huge tires can reduce a vehicle's acceleration,
but that's only a factor when the wheels and tires are a substantial
fraction of the vehicle's mass.
Other than monster trucks or beginner-designed RC or robot vehicles, it
usually does not matter much.

Choosing an aspect ratio is a more current issue for engineers.
A tire can protrude for beyond the rim to a distance larger than it is width,
or be "thin and wide" with less sidewall.
Thin and wide can have less lateral flexure during extreme cornering,
and I think there is some technical reason why it is a more viable option
than it used to be.
Certainly wide tires must have radial-ply rather than bias-ply reinforcement,
so the wide outer face can remain "flat".

[Dipper]

Is that the correct tyre size for 18's? Generally for a given model, the smaller the rim, the larger the tyre profile.

Not sure I agree that smaller wheels give a smoother ride. Larger diameter wheels(overall diameter Inc tyres) roll better than smaller ones as the angular contact with bumps is less. Think bmx v mountain bike. However what makes greater profile tyres comfier and better handling on typical roads is the volume of air in them and the extra sidewalk flex. Honda stuck to their guns with the original integra type r(widely regarded as the best handling front driver ever) back in the late 90's and shod them with 15" wheels and iirc 55 or maybe 65profile tyres as they handled better.

[chunky79]

Now the pic's have been dispatched you will get a welcome form me, WELCOME DIPPER.
Looks a lovely motor. Is it standard and do you have any plans to changed stuff yet?

dunc

[Dipper]

Cheers. It's completely standard. My first task is to get the timing belt done and possibly some paintwork but that's not urgent. With the warranty on top that's a couple of k thrown at it already! I did budget 4k to get it right though. If I was to pick any issues I'd like to improve it would be the suspension. It's great on smooth surfaces but unsettled down bumpy b roads(of which we have a lot). I'd also like to chip it but not sure how the warranty company will view that should the gearbox pack in! We'll see how it goes.

[mavada]

[mrmule]

i thought pedal vibes was the first sign of the DRC playing up?

Nope. Still happens in mine with KWs, and happened in my previous with H&Rs.

Welcome Dipper! Cleeeean wheels

[Billiemapped]

Hello and welcome Dipper

Nice car sir...

[Shoppinit]

i thought pedal vibes was the first sign of the DRC playing up?

Nope. Still happens in mine with KWs, and happened in my previous with H&Rs.

Welcome Dipper! Cleeeean wheels

Oi ! Don't misquote me! Especially on something so fundamentally wrong!

Mavada:

the rolling diameter of 255/35/19 is 66.11cm with a circumference of 207.69cm

the rolling diameter of 255/40/18 is 66.12cm with a circumference of 207.72cm

So actually the 18" will make for slightly longer gearing, making your car 0.015% slower than mine

Sounds like a good excuse for putting some 19" on

[Shoppinit]

It's great on smooth surfaces

Where you don't need suspension...

but unsettled down bumpy b roads(of which we have a lot)

...where you do.

Sounds like your DRC could be kaput. Mine sticks to the road like a rash to a 50 year old prostitue's axe wound.

Don't worry, you're not the only one, not by a very long way. Stick some billies on

[mavada]

yes youre right Shoppinit, i thought i had 18x30 but its 18x35... sorry about that...
as mentioned before i like the mtm bimoto but as you said, they are 8.5 width.
i like the s8 20 inch also... i think they look nice with my mugello blue rs6 and lowering a bit.

im still in doubt which to put on, the billies or kw...

Also looking for parts to refresh my atf, planning to do it myself.
As shown in the pic i think i need the following numbers:
5
maybe 8 also
10
28

and 10 liters of oil you mentioned in your previous post:

ZF Lifeguardfluid5 (ZF No. S671 090 170):
Audi / VW Oil No. G 052162 A1 / A2 / A6
BMW Oil No. 8322 9407807
Citroen Oil No. Z 000169756
Jaguar Oil No. JLM 20238
Mercedes Benz Oil No. A 0019892203
Peugeot Oil No. Z 000169756
Porsche Oil No. 999.917.547.00

what are the costs of this stuff?

[Shoppinit]

You should start another topic rather than hijack Dipper's

[mavada]

yes youre right, sorry dipper!!!

[andyt]

5 mins after he left the passenger door has started playing up. takes half a dozen attempts to get it to shut properly!

Mine does that, and others have reported it too. I find that it's a case of shutting it gently, the more you slam it (in that way that mother-in-laws always do), the less likely it is to shut.