back tyres are knackered queston

[Hinesy]

Apologies, as Im new here, if this has been previously discussed.
I have an S reg S4, and in the last 20,000 miles have had to change my back tyres twice as I've discovered them to be completely worn to bald. I do a lot of driving ( these 20,000 done since October) but am unsure if its just the mileage thats done them in, or a more serious problem.... it's 90% motorway driving, not too fast constable, nothing mod'ed or out of ordinary
Any suggestions ? Help etc

thanks

[wazza]

Only 10k for a set of rears is pretty poor going, especially for 90% motorway driving.
Possibly due to pressure, but more than likely it's the compound. Which brand tyres are you using? [now say they are Pirellis [img]images/graemlins/confused.gif[/img]]

Welcome to the good ship rs246 and I hope the ride will be enjoyable [img]images/graemlins/grin.gif[/img]

[jeffw]

The question is how many fronts are you getting through in the same period ?

[Hinesy]

thanks for the welcome!



well today I've bunged 4 P zero's on it - fair deal at 105 each, so in total
FRONT
replaced once ( today) - regular/even wear on each - over a period of 21,000miles - had a bit to go on them but were nearly illegal

REAR
twice over the same distance but they were completely like slicks when I noticed - much more wear than the front.


Will get an alignment done tomorrow but just wondered if anyone else had this kind of problem??

[jeffw]

Is this all the way across the tread ???

The only thing that I can think that would cause is (apart from alignment) is Handbrake stick on.....

[Hinesy]

Jeff
it is all the way across - there's a very slight feathering which makes me wonder if its alignment...

[DavidT]

Welcome.

On the road, my tyres wear slightly faster on the front with 2mm left on the fronts, the rears are at 3mm.

I have had a set do 20,000 and one that did 9,000 (with the front-rear difference described above) so I reckon you must have a problem for there to be such a discrepency front-rear.

Could be brakes, could be transmission related, but I think alignment is by far the most likely cause.


Good luck with it.

David

[Hinesy]

thanks Dave for that.
I'll let you know how it gets on after my alignment...

[toasty]

Mine is running Goodyear Eagle F1s.

I've done about 10,000 (mainly motorway) plus one trackday on a set that were partially worn when I bought the car and there is still 3mm of tread left.

Based on this I would hope to get around 20,000 from a new set based on me switching them front to back after 10,000miles.

HTH

[Golich]

Hinsey,

I have noticed the same problem as you with my 97 S4 Avant. The wear is slightly more pronounced on both the outer edges of the rears. But nothing really. I also spend the majority of my time on dual carriageway or a low speeds round town. The only difference is, I have 320bhp.

I've had the four wheel alignment carried out by Star Performance who tell me it's fine. I believe they use the same kit as AMD.

However, I have an additional problem with the rear end of my car ever since I bought it with 34K miles it now has 52K.

While travelling along in a straight line if I cross certain potholes/manhole covers I feel a side thrust from the rear of the car. Also the rear end is very Skippy over rough roads if travelling quickly over them. Which make me think the shocks are past there best but the damping seems fine from a stationary check. i.e. pushing down on the car it doesn't continue to bounce.

I've written about this on several sites. Once under the heading of Quattro handling characteristics as I feel my experience of my 1st 4WD car is that it's very like a rear wheel drive car, in that it's always the rear end that steps out while under hard acceleration. It's generally ok if your not trying to put too much power down with the usual understeer and the rear end has only stepped out in damp or wet conditions.

I'm convinced that either the shocks or the many bushes are shot or some bolt is slack somewhere. I also thought the rear diff. or torsion diff. may be to blame. However, the problem has not really got that much worse over 18K miles which makes me think the diffs must be ok.

I've had a couple of brief looks under the car and everything looks fine. The guys at Star didn't notice anything. But I don't think they understood that I was experiencing a side thrust while travelling in a straight line.

I've got the Erwin manuals and plan to have a real good inspection sometime soon prior to replacing the shocks.

[Hinesy]

Golich
interesting stuff I get a slight left pull when I accelerate but nothing untoward...
whats a full fuel tank run on ? mine's a 97 actually and i get just over 300 miles on the full tank - I was trying to work out if the tyre problem was affecting my mileage too....



PS SHould be back tyres are knackered QUESTION, not queston.... sorry for the speling [img]images/graemlins/wink.gif[/img] [img]images/graemlins/smirk.gif[/img]

[jeffw]

If the problem was alignment you would see part of the tyre worn before the others (inside or outside edges normally). If you got even tyre wear then it's unlikely to alignment.

It is the sort of tyre wear you would get from a RWD car ( 2 sets of rears to 1 set of fronts). Normally a FWD car will wear evenly across all 4 tyres with the fronts experience slightly more wear due to steering & braking inputs.

[Nige_RS4]

Jeff, mmmm my last 8 FWD company cars had on average a 6:1 front to rear tyre replacement ratio - one front set lasted less than 8k miles (Rover turbo diesel) - glad I wasn't paying !!
Nige.

[jeffw]

Sorry, I meant Four Wheel drive (should have put AWD....too early in the morning)

[Dippy]

I have none of the problems described, although the insides of my fronts are wearing faster which I think is due to the camber set up by AmD.

My front tyres definitely wear quicker than my rears, but not at 2:1. My best guess is that it's about 4:3.

People who don't have 4WD usually assume that 4WD has even wear. However of course the drive split is rarely 50:50. Isn't it normally around 40:60 front:rear for the S4.

In my mind this would suggest that the rears should wear quicker than the fronts, as Jeff suggests, however I suppose the fact that the fronts are steered as well as driven would make them wear more for this reason?

Maybe my car has been putting more torque to the fronts than other owners here. My driving has mainly been on B roads so I suppose I might get a lot more torque shift between front and rear than those who mainly use A roads and motorways???