S4 B6 different sized tyres on frond and back - is it going to confuse systems?

[mjhamilton]

so.. the S4 I purchased a month ago could really do with new boots on the front they are legal but the outsides are worn, I wouldn't want to hit a puddle on a bend so want to change then asap

Stock tyre is 235/40 R18 and it would seem the previous owner has fitted a premium brand but to save around £20 a corner has fitted 225/40 R18, these don't even work on the +/- 1 rule

So here is my question
I want to buy 2 new Conti5XL's in the OE size - I will put these on the back and have the slightly smaller tyres on the front - will this mess up or confuse any systems such as ABS or ESP??.... the size is 1.2% smaller than OE so the front wheels will cover 1.2% less distance per rotation

Any thoughts on this - do not really want to buy 4 in one go as the rears (soon to be fronts are Conti2XL's in great condition) - do I just refit with the same size as they have now?

[Guest 2]

Ideally you should have the same all round, your insurance might also be compromised since you're not running original spec sizes.

I know when I put my winters on which are 205/55/16 I had to inform my insurance of the change in tyre size.

[mjhamilton]

'.. already covered on that one.. they don't care unless their is a massive difference or tyres are for another season - this has been confirmed

I may just suck it and see...

[size12]

Also being a awd you run the risk of killing the diffs/gearbox due to the wheels having a different rolling radius.

[mjhamilton]

Hmmmm I was actually mulling that over during my drive out this evening - 1.2% difference could be bad on an awd

So no simple answer to this one - I am now thinking about replacing all four but the ones on the rear are almost new

[Guest 2]

Sell them as part worns?

I'll be doing the same with my fronts when I replace my rears as I like all 4 to be the same.

[mjhamilton]

Wow I have spent most of my evening researching - conclusion = same size on all four corners and even same brand and type

Torsen differential can just about cope with tyre wear and nothing more so doing different sizes on each axle could at best give odd handling and at worst cause the differential to overheat, bind, wear or even fail

So it'll be 2 at this size or 4 at the OE size for me then

[mjhamilton]

can anyone see any issues with these?? Four (4x) Avon ZZ5 95Y XL 235/40/18 R18 Set of Tyres | eBay (http://www.ebay.co.uk/itm/Four-4x-Avon-ZZ5-95Y-XL-235-40-18-R18-Set-of-Tyres/370739398816?rt=nc&_trksid=p2047675.m1851&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%2 6asc%3D74%26meid%3D556707101391310729%26pid%3D1000 05%26prg%3D1048%26rk%3D2%26rkt%3D4%26sd%3D40039183 0076%26#ht_1425wt_1157)

this is a very, very good deal for 4 tyres in the correct OE XL size - the Avon ZZ5 also has a good following - I do about 3-5k a year of casual Cabriolet driving so I think they will be more than adequate for my needs

Any input?

[Guest 2]

Im pretty sure Zollaf rates these highly, which type of Avon I'm not sure but Avon in general gets good words from him.


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[size12]

Avon's are a decent tyre shouldn't have any problems with those.

[mjhamilton]

at £462 inc fitting, balancing and disposal (I will resell the 2 good Conti's) this is an amazing price to get me up to OE size - I was looking at minimum £600 for Conti, Pirelli or Goodyear....

... am going for this one as there is a National in the town near me

[Doctle Odd]

As the circumference is the same the tyres would have litte or no effect on AWD or sensors but as the widths are different they would affect cornering etc. Very good deal you got on the tyres in Ireland that would be 200 yoyos a corner

[mjhamilton]

As the circumference is the same the tyres would have litte or no effect on AWD or sensors but as the widths are different they would affect cornering etc. Very good deal you got on the tyres in Ireland that would be 200 yoyos a corner

my initial dilemma was to replace the fronts with OE's that would have had a 1.2% larger rolling radius than the rears that are on their already - apparently this is a big no no as the different rotational speed between front and rear will make the driveshaft TORSEN diff work more than it should..

.... so any how I am going to put OE on all four corners which will eliminate this in the future - also the 1.2% extra rolling radius should equate to better MPG as I will use less RPM for the same speed... not a lot I know but every little helps

Any one want 2 good condition ContiSport2 225/40/R18XL tyres :)

[Doctle Odd]

I think you can "tell" the car using VCDS if you have fitted larger radius tyres

[mjhamilton]

yes you can... but they must be the same on each axle

[zollaf]

yes, as chris says , i rate those avon zz5's very highly indeed. ok, they don't last as long as some, but the grip, especially in the wet is outstanding. i hit about 6'' of standing water whilst making good progress, thought that was it yet nothing happened, the tyres just bit in and coped. had them on the old 16v coupe and never managed to get that out of shape, they just inspire total confidence.

[mjhamilton]

then I'm in... thanks... my car is a toy, I don't commute for work so it does 3-5k a year - with this in mind longevidy is not the primary I just want something that will make the car handle nicely in the dry and behave in the wet

Sounds like these tick all the right boxes

Cheer for the input

[mjhamilton]

Well pleased to say that I had them fitted an hours ago - OE tyres looks a little fatter on the 18" but actually fill the arch better than the 225's - also the roads are greasy and the Avons are really very good so am a happy boy - total price = £470 fitted which IMO is a very good price indeed

Bonus is that the 2 x Conti2's that came off the back are in very good condition - no splits, damage or repairs and both have over 4mm tread evenly across the whole tyre - so will see if anyone wants these on ebay