When is the need to replace all 4 tyres

[PMAX]

My local Audi dealer has informed me that my current tread depth on my tyres measure 2/4/2 on both front tyres and 4/4/4 on the rear. They have stated that all four will need to be replaced when the front get to there limit due to the Quattro 4 x 4 system.

Is this neccesary as I assume that when the front tyres need to be replaced that the rears could still only be 50% worn.

Can anyone give me some advice, as before this statement I was going to replace just the two front tyres, but know I wonder if I need to wait and replace all four. I wonder what the maximus difference in the circumference of the tyre is related to the tread depth, there must be a guideline.

Current tyres are 255/35 x 19

Any help would be appreciated.

[ArthurPE]

there is a maximum differential
iirc it's 2/32nd's

I'll try to dig it up, pretty sure it's been posted here?

[ArthurPE]

from Tirerack
Audi As published in their vehicle owner's manual, "rolling radius of all 4 tires must remain the same" or within 4/32-inch of each other in remaining tread depth.

[kay]

I recall my dealer saying there musnt be more than a 4mm difference between front n rears. Actually I think I may have recalled incorrectly cos that's a big difference, doesn't sound right. Sorry, I'm no help lol.

[adsgreen]

4/32 just a tad over 3mm

[lengster1]

Your rolling radius will be the same an all your tyres its only the edges that have feathered on your fronts and this is an rs4 thing it would seem,if this meens your full set of tyres are junk at 4mm then its a bit ott

[Steve_C]

I can understand a tyre wearing on either the inside or outside if the alignment is incorrect but how can it wear on both at the same time and not in the middle?

[wolfgang]

^ Low pressures?

[ShouldveBeenAGerman]

So if you get an unrepairable puncture you need four new tyres or a dodgy part worn

[Revolution]

sounds like under inflation to me also.

you should be able to get away with a pair on the same axle

then you have 1 spare for emergencies

[CRSRS]

Just bought mine from Audi and when I looked the fronts were different makes, same brand on the rears. Asked Audi CS and they told me that as long as the tyres were the same on the same axle it was OK. Forced the dealer to replace both fronts to same make. They didnt seem to worried that the rears were about 6mm with new pair the front.

[PetrolDave]

So if you get an unrepairable puncture you need four new tyres or a dodgy part worn

Yep. Unless you want to risk damaging the centre Torsen diff.

[PMAX]

Many thanks to you all for your responses, it is now clear what I need to do and that is to wait a while and see what the tread depth differences are in about a months time. I think the statement about under inflation is correct as I have been running at 36 PSI all round since having the car 6 months ago, I have now pushed this to 39 PSI on the fronts and see what effect this has.