Bad tyre wear

[220bhp]

I have just put my s6 in for an M.O.T and it failed on both front tyres I have to say I was shocked ,they are P 0 rossoes on new audi s4 18in wheels 225 40 ,both are fine across the tread about 100000 left I would say but the inside corner is completley scrubed like 45 degrees or so , the tyres have done less than 5000 miles the back ones are like new ,the tracking is spot on 4 wheel allinement is ok so why so much wear .The tyre people say its because the larger wheels flex inwords and cause the wear [the original are 16in ] but this is not surely the case with these wheels on an s4, so prehaps the s4 has a different set up I dont know but it just cost me £211 for two new avons I think I might give the more exspensive rossos a miss untill I find out and may change the wheels if the avons do the same .any ideas anyone before I go bankrupt

[S2 Ant]

i would guess that when cornering at speed the tyres will flex over and as they are low profile tyres, this flex will wear the corner of the tyres more, causing this wear.

Ive noticed that my front left has this kind of wear, usually because most of the corners i take quite fast around town are big roundabouts, so the car is turning right at speed causing the front left to flex under.

If that makes sense.

[220bhp]

Thats quite interesting ant but I have always driven hard on the original 16in wheels mostly whith continentals an they have all worn on the outside and usualey at about 10 to 15000miles seams strange

[S2 Ant]

i doubt your 16" tyres had a low profile tho, they have more side wall, so go up then roll over to the tread, whereas this sidewall is much less apparent on lower profiles, esp on my 35 profile tyres

[dan_b]

Are you absoloutely sure your tracking hasn't gone out - uneven tyre wear across the front tyres is very commonly caused by bad tracking. How hard are you driving your car though - it could just be you're enjoying cornering!

[dan_b]

Also, what tyre pressures are you running - under- or over-inflation can cause very odd wear patterns as it changes the actual shape of the contact patch.

[audiman]

Alignment prob IMO. Get the camber rechecked. Also on those AFAIK the castor is also adjustable.

[Keeper of The Kitten]

On the front tyres:

Toe OUT
Causes the INSIDE shoulders to wear excessively.

Toe IN
Causes the OUTSIDE shoulders to wear excessively.

UNDER inflation
Causes BOTH shoulders to wear excessively

OVER inflation
Causes the MIDDLE of the tyre to wear excessively

16" wheels would have low profile tyres, but not as low profile as the 18" wheels. The aspect ratio of a tyre that isn't described as low profile, is 80% - anything lower will be quoted on a tyre sidewall (usually you see it from 70 downwards).

I was trying to explain to a Subaru owner (the guy who owns my local chippy!) that he really needs to inflate a bit more with larger wheels and lower profile tyres, he insisted on the line "if it needs xx psi that's what I use - but I am wearing the shoulders off excessively" ...I couldn't make him understand that a little more pressure would make the whole tyre do some work, and reduce the uneven wear.

If you're losing the inside shoulder, the only hard cornering that can cause it would be to the unloaded inside tyre - as it droops away and the car rolls outwards, putting that tyre onto it's inside edge. The wear described on the outside of the original 16" wheels/tyres is to be expected as the loaded tyre on the outside of a corner rolls over it's own tread and onto the shoulder/sidewall.

I don't believe the wheel flex argument. Sounds like tyre fitter speak for "I don't know". In fact it sounds like total boIIocks. Wheels do flex but it's unlikely that they will deform sufficiently to cause the shoulder wear, they are more likely to move as a whole (the rim gets pushed across relative to the hub) so the angle at the contact patch doesn't change much.

Toe OUT seems far more likely than anything else, though it could be a result of flex in the suspension bushes. Tracking is best checked after bush renewal!

__MDC__

[220bhp]

The tyres are running at 36psi the tracking was checked at audi so was four wheel allignment so I just dont no.

[audiman]

Tracking may be ok when checked, but if the bushes are old and weak, the geometry will alter when driving. Same if something is worn. Are the lower arm bushes original? They tend to become soft on those cars. Also roll bar bushes in the lower arm become soft and cause the alignment to be thrown out during cornering etc.

[missmouse]

exact same problem has occured on my S2- severe inside shoulder wear. I was wondering if i had faulty tyres! tracking is ok AND if it was out that much you should be able to feel feathering across the whole tread but the main tread area is evenly worn (in fact not very worn at all!)
Any more ideas guys?

simon

[Corey]

When was the last time you had your top mounts replaced. The S4/6 is very susceptable to knackered top mounts which would cause the uneven wear.
Or has the car been lowered? Lowering an S4/6 also prevents the camber being set correctly and cause the same problem on the tyres.

You should have seen my old tyres...

[iain1067]

I have just replaced the top mounts on my UrS6 i must say they ones i took off didn't look or feel worn at all, thankfully it's like 10 minutes per side to do. I would favour the control arm bushes and anti roll bar bushes are shot, it is weak point on these cars, this is next on my agenda. My car is running on 17 inch wheels with 245/40 tyres so i doubt it's a bigger wheel problem. The only other bushes up front would be the subframe bushes which the lower control arm attaches itself too.

Iain

[audiman]

incorrect camber settings will cause that type of wear