S4 vs A4 rear wheel's well difference

[Filipão]

Hi Knowledgeable Ladies and Gents.

Why does my S4 have a kind of reinforcement on the rear and my wife's A4 does not?

Fronts are alike.

Thank you!

 

[DohNut]

It’s to do with legislation around the wheel/tyre protruding beyond the bodywork. My A4 has them because I specc’d the upgraded S4 alloys.

 

[Filipão]

It’s to do with legislation around the wheel/tyre protruding beyond the bodywork. My A4 has them because I specc’d the upgraded S4 alloys.

Thank you, it would make sense if tire width and offset were not the same.

I have 8W0601025H - 8.0x18 ET40 on my wife's A4 and 8W0601025BE - 8.5x19 ET40 on the S2. Both running on 245 tires and ET40.

Maybe they have different tracks?

 

[cuke2u]

Even our 2013 fiesta had them..

 

[SMI77]

....ummmmm, if the reinforcement is to do with protrusion of the wider tyres/wheels, and mindful that they do not protrude past the bodywork OEM, why doesn't the reinforcement extend past the bodywork?

Trivia - Audi confirmed to me that the A5 OEM tyres are 255mm as it has larger wheel wells.

 

[Filipão]

....ummmmm, if the reinforcement is to do with protrusion of the wider tyres/wheels, and mindful that they do not protrude past the bodywork OEM, why doesn't the reinforcement extend past the bodywork?

Trivia - Audi confirmed to me that the A5 OEM tyres are 255mm as it has larger wheel wells.

Yes indeed.

Thank for the trivia! Unfortunately I'm stuck with the sizes mentioned on my C.O.C., no pun intended.

 

[DohNut]

It’s not reinforcement, merely a trim piece.

 

[rum4mo]

I'd not expect Audi to be dumb enough to need anything added to the bodywork depending on which tyres/wheels are fitted.

That type of plastic addition is normally to help with deflecting road grit etc from the edge of the well arch, like the Fiesta and the B8.5 Avant and many others.

 

[Spaceman_RS3]

I'd not expect Audi to be dumb enough to need anything added to the bodywork depending on which tyres/wheels are fitted.

That type of plastic addition is normally to help with deflecting road grit etc from the edge of the well arch, like the Fiesta and the B8.5 Avant and many others.

Believe it it’s to conform with the law around protruding wheels when viewed from the top of the wheel arch the larger wheels with lower offset poke more and require this little addition to conform to the law that’s it no other hidden meaning

 

[DarkyUK]

I'd not expect Audi to be dumb enough to need anything added to the bodywork depending on which tyres/wheels are fitted.

That type of plastic addition is normally to help with deflecting road grit etc from the edge of the well arch, like the Fiesta and the B8.5 Avant and many others.

I agree, its normally to deflect stones etc, probably there to protect the body work on the more premium vehicles, i'll check if my S5 has them

 

[SMI77]

Believe it it’s to conform with the law around protruding wheels when viewed from the top of the wheel arch the larger wheels with lower offset poke more and require this little addition to conform to the law that’s it no other hidden meaning

errrrrrr...if the protusion did extend to the top of the wheelarch I may agree with you, but it doesn't. Not on ours, anyway.
To me, it does not extend low enough to act like a mudflap to protect the lower bodywork aft of the rear wheel.

 

[Daggerit]

errrrrrr...if the protusion did extend to the top of the wheelarch I may agree with you, but it doesn't. Not on ours, anyway.
To me, it does not extend low enough to act like a mudflap to protect the lower bodywork aft of the rear wheel.

I haven't looked yet, but I imagine that it would be because the bodywork narrows slightly behind the tyre so as you look down from above, that little piece of plastic might be enough to stop you seeing the rubber that you otherwise would. That's the only thing I can think of.

I think that the new Renault Megane RS has something similar if I remember rightly, but it's part of the bodywork but definitely put on for that purpose according to an interview I watched.

 

[Daggerit]

There you go, you can see the bulges in a similar place on here. And as I said, they’re definitely there for that legislation described above.

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[SMI77]

OK. You must be in Sales ;-)

 

[Daggerit]

OK. You must be in Sales ;-)

Maybe I should be! Lol. Actually I'm an engineer so I sometimes remember these little things because I think they're interesting solutions to getting around legislation.

 

[pagenotfound]

I'd always assumed they were some sort of aero trim to do with the s-line package but the explanation re tyres not protruding beyond bodywork seems to make sense. They certainly aren't for reinforcement - one of mine became became detached when a clip came away and it seemed to only secure to the flexible wheel arch liner. They would also be chocolate teapot worthy as stone deflectors.

 

[rum4mo]

errrrrrr...if the protusion did extend to the top of the wheelarch I may agree with you, but it doesn't. Not on ours, anyway.
To me, it does not extend low enough to act like a mudflap to protect the lower bodywork aft of the rear wheel.

Exactly and correct, the rules only state that when the car is viewed from above there should not be any tyre area showing and the intention was that it is only the top area of the tyre/wheel as if it was any other points on the tyre/wheel then negative camber would make things worse - and most cars run negative camber.

So, in the unique case of Audi supposedly putting to market a run of the mill car that in standard form, would need wheel arch extensions - where would be the logic in that, in as much as, trim falls off - car now illegal?

Certain upmarket variants of run of the mill cars have and will continue to, from time to time end up being placed on the market with purpose built widened wheel arches due to the wheel size fitted, that is true.

Audi has had in the past some issues with stone damage causing bodywork to need repairing/replacing under warranty.

 

[rum4mo]

There you go, you can see the bulges in a similar place on here. And as I said, they’re definitely there for that legislation described above.

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In that example, yes, but you can see that the bodywork has been shaped to provide streams of mud and stone ending up on the rear bodywork, but the tyre line is still inside the original bodywork line at the top of the wheel arch - and that is a special version of that car.

Edit:- lets get down to real facts here, I can't say if that deflector shown in the original picture is part of the wheel arch liner or an extra part, but after the problems with some A4 B8 needing sorted due to paintwork damage from flying debris, the A4 B8.5 or at least some of them appeared with that same plastic extra part and it is listed as a "deflector" and not a "wheel arch extension".

 

[cuke2u]

Part number 25?

 

[Daggerit]

Part number 25?
View attachment 166155

That's the one I think! 'Wheel cover' seems to point towards the legal thing rather than the stone damage I think. Incidentally, I've had no stone damage issue on my B9 like I did on my B8.5 and I've got spacers on the B9 as well that I think would probably make it worse.

 

[rum4mo]

I would have expected that “lip” to be presented vertically and not horizontally if it was the thing that I have called a stone deflector, they don’t need to be strongly fixed on to work as stone deflectors the B8.5 ones only had a couple of locating dowels moulded into them and strong double sided tape.

 

[cuke2u]

I don't know if it is an exact science but the line from the 'wheel cover' rotates before it ends inside the wheel well...

 

[DohNut]

My 2011 Q5 S-line had them too , so not a new thing or unique to the A4 .

 

[paul wev]

My 2013 sq5 tdi with 21” wheels does too


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[rum4mo]

I don't know if it is an exact science but the line from the 'wheel cover' rotates before it ends inside the wheel well...

The original stone deflector is shown for the front wheels and is presented vertically, I think that for the rear wheel cover, the line "rotating" is only to keep clear of other parts/details, by the way, that parts layout also shows a "wheel cover" for the front wheel arch and it seems to be at the top of the wheel arch, and presented horizontally.

Looking again at the OP's original picture, the profile of what is shown looks exactly the same as the stone deflectors that get fitted to the front, at least on the B8.5 S4, B8 S4 did not get these parts fitted, it seems until they had been reworked to sort out rusting wheel arches which that front stone deflector was supposedly fitted to prevent. Also that picture shows that plastic part to remain within the wheel arch profile and not sticking out, which you would expect if it was needed to allow the car to comply with regs concerning keeping all wheels within the width of the car.

Edit:- looking at the parts layout again, are these "wheel covers" not just hidden parts to support/hold the wheel arch liner in place?

 

[cuke2u]

Have a look at it yourself...
http://www.realoem.me/Audi/RDW/A4Q/2017/849/R/8/853/853000

 

[rum4mo]

Have a look at it yourself...
http://www.realoem.me/Audi/RDW/A4Q/2017/849/R/8/853/853000

I think that you would need to find an up to date proper version of the parts listing, like EKTA - which incidentally seems to be quite difficult to find as most of the better unofficial versions seem to have been closed down! I don't think that the part that you have found in that parts listing is the one shown in the OP's picture, though I'd reckon/guess that a genuine copy of Ekta would show it as it is showing the part that gets fitted to the front wheel arch, ie reference 15.

 

[rum4mo]

Hi Knowledgeable Ladies and Gents.

Why does my S4 have a kind of reinforcement on the rear and my wife's A4 does not?

Front are alike
Snip --- Snip
Thank you!

Hi, did you buy your car brand new?
Also, your top picture, that is the rear of the rear wheel arch?
That thing that I am calling a stone deflector, it is angled/tapered at the bottom, but your front one should be angled at the top.
The reason why I am asking these questions is, to me it looks like some one has just fitted probably, a set of front wheel arch rear mounted stone deflectors onto the rear of your rear wheel arch - which is okay, but I would have expected them to be fitted the other way round, ie the angled/tapered end at the uppermost end and the squared off end, if the other end is squared off, to be at the lowermost end so that when/if rear mud flaps are fitted, the top of them would contact that point so that the mud flap and that stone deflector work seamlessly together and protect the rear of the car's body from stones and any other material being thrown up - unless Audi has some other new idea on how/where to fit these items.

 

[cuke2u]

It is in the exact same position our fiesta had them in to cope with the larger lower profile tyres ford fitted as standard.
How can you say 'someone' has fitted them when other owners have also got them on their A4 and S4's and isn't unique to that car either.
Similar ones fitted as standard to the S3 if it has 19" wheels from the factory https://www.audi-sport.net/xf/threads/part-number-for-these-not-sure-what-to-call-them.377500/ post #28.

 

[pagenotfound]

They are on my A4 Avant rear wheel arches as standard fit from factory. Obviously some don't have these as standard so the debate is what is the feature that determines if they are fitted. If they were to protect the paintwork from stones then surely they would be on all cars, and regardless, it is a very small area they would protect.

To back up the argument for the protrusion of the tyres, if you stand behind the car and look down the rear wing, my tyres would protrude from the bodywork without the trim due to the kerb protection rim on my 245 35 R19 Hankook tyres fitted to mine. The plastic trims seem to just extend the wheel arch enough to maybe comply with some regulations.

 

[cuke2u]

Here as well https://www.audi-sport.net/xf/threads/s3-plastic-trim-on-wheel-arches.326367/

 

[rum4mo]

It is in the exact same position our fiesta had them in to cope with the larger lower profile tyres ford fitted as standard.
How can you say 'someone' has fitted them when other owners have also got them on their A4 and S4's and isn't unique to that car either.
Similar ones fitted as standard to the S3 if it has 19" wheels from the factory https://www.audi-sport.net/xf/threads/part-number-for-these-not-sure-what-to-call-them.377500/ post #28.

I'm just asking the question of the OP to see why/how his had been fitted as they are they are upside down when compared with how they were fitted to B8.5 S4 to reduce/remove wheel arch turned in face stone damage which rapidly became rust damage and so needing to get covered FOC under warranty. B8 S4 did not initially get them fitted and cars with the 19" wheels did suffer from this area getting damaged, legalising the bigger/wider wheel option does sound more manly, but I'm not convinced that that is the reason, it may be the reason given by sales persons as they tend to know not too much and like pushing the customer towards options like 19" wheels on A4 B9. I'll stick with protecting the paintwork from stone damage that will cause Audi much spending of their own money to sort out in early years of these cars life.

Edit:- just consider this, if a car's optional wheels stick out so far as to be illegal by car construction rules, on full suspension compression the tyres will contact the edge of the wheel arch and be very dangerous, clipping on additional plastic parts to the existing shape of body work will not stop any wheel to body contact.

 

[Daggerit]

I'm just asking the question of the OP to see why/how his had been fitted as they are they are upside down when compared with how they were fitted to B8.5 S4 to reduce/remove wheel arch turned in face stone damage which rapidly became rust damage and so needing to get covered FOC under warranty. B8 S4 did not initially get them fitted and cars with the 19" wheels did suffer from this area getting damaged, legalising the bigger/wider wheel option does sound more manly, but I'm not convinced that that is the reason, it may be the reason given by sales persons as they tend to know not too much and like pushing the customer towards options like 19" wheels on A4 B9. I'll stick with protecting the paintwork from stone damage that will cause Audi much spending of their own money to sort out in early years of these cars life.

Wasn’t the stone damage issue at the very bottom of the arch though? Rather than halfway up where the bumper and arch meet?


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[Daggerit]

Also, I’d argue that it’s more likely to be the legislation issue if various marques have them fitted as people have explained, especially with some cars having the same sort of thing moulded into the bodywork and painted like the Megane above. Wouldn’t be very good for reducing paint damage if your using a painted part to stop the stones I wouldn’t have thought.


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[rum4mo]

On the front wheel arches the damage was half way up - I've edited my posting since you quoted it by the way.

 

[Daggerit]

I don’t agree with your edit though as I’m pretty sure mine protrude to the rear of the arch section now that I have spacers on but they don’t rub under compression even with lowering springs on. I’ll take a look tomorrow to confirm the view from the top down though.


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[rum4mo]

Also, I’d argue that it’s more likely to be the legislation issue if various marques have them fitted as people have explained, especially with some cars having the same sort of thing moulded into the bodywork and painted like the Megane above. Wouldn’t be very good for reducing paint damage if your using a painted part to stop the stones I wouldn’t have thought.


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That Megane, is not a standard Megane, it is a Megane RS so it is possible that reshaping of the body work was necessary for it to comply, I don't question that, these other cars mentioned are just standard run of the mill cars so only have the normal shaped body work.

 

[rum4mo]

I don’t agree with your edit though as I’m pretty sure mine protrude to the rear of the arch section now that I have spacers on but they don’t rub under compression even with lowering springs on. I’ll take a look tomorrow to confirm the view from the top down though.


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If you are an engineer you should be taking a logical approach to this and not just be steered by sales talk.

Quite a lot of cars out there will have sections of their tyres visible as built at the factory and seemingly comply with the ruling or the intention of the ruling which I think was initially to protect pedestrians from making contact with the rotating wheels, but we both know that in reality it can still happen.

Edit:- so what is stopping your spaced out wheels from contacting the body work if they stick out?

 

[Filipão]

Here as well https://www.audi-sport.net/xf/threads/s3-plastic-trim-on-wheel-arches.326367/

@cuke2u not the same at all, sorry, on mine (S4) they don't stick out at all

 

[Filipão]

Hi, did you buy your car brand new?
Also, your top picture, that is the rear of the rear wheel arch?
That thing that I am calling a stone deflector, it is angled/tapered at the bottom, but your front one should be angled at the top.
The reason why I am asking these questions is, to me it looks like some one has just fitted probably, a set of front wheel arch rear mounted stone deflectors onto the rear of your rear wheel arch - which is okay, but I would have expected them to be fitted the other way round, ie the angled/tapered end at the uppermost end and the squared off end, if the other end is squared off, to be at the lowermost end so that when/if rear mud flaps are fitted, the top of them would contact that point so that the mud flap and that stone deflector work seamlessly together and protect the rear of the car's body from stones and any other material being thrown up - unless Audi has some other new idea on how/where to fit these items.

@rum4mo Yes, both S4 Avant and A4 Avant were new and are untouched.