Running 235 Tyres Front and 225 Tyres Rear on Audi S3 - Damaging to Haldex?

[guile]

hi all,

i would appreciate a response from anyone who has a lot of experience with the haldex system on an audi s3 2010 year model.

if the following info makes sense i thought i'd start by providing the background for my question; the short version...

i'm currently looking at a new wheel and tyre combo and want to make sure i don't scrub my tyres on the arches but also want to maximise my grip.

i hope that 235/40/18 will work all round but think it will be close on the back, surprisingly i think it will be ok on the front. my plan so far is to buy a pair of 235's and try them on the back. if they scrub i will move them to the front and order a pair of 225 for the back.

i have never heard of running wider tyres on the front than on the back but note that audi run this set up on the rs3 to reduce understeer (Tyres: 235/35 Front, 225/35 Rear. Both of them are 19").

my question is if i run 235/40 on the front and 225/40 on the rear of my s3 will it screw my haldex due to different rolling diameter.

the question has been asked on the the thread below but does not appear to be a very conclusive answer:

http://www.audi-sport.net/vb/a3-s3-s...3-quattro.html

i would be very grateful if anybody categorically knows the answer.

[guile]

answered my own question if anyone else would like to know:

Haldex wrote:

Hi Franz,

Yes, we do compensate for tiresizes up to 4%. This since we read the wheel speed and the driveshaft can understand if you have a minispare, worn down tires or different sizes.

Best Regards,
Mats Johansson
Haldex Traction AB
Detroit

Tire Size 1
225/40R18 Imperial Metric
Section Width: 8.86 in 225.00 mm
Overall Diameter: 25.09 in 637.20 mm
Sidewall Height: 3.54 in 90.00 mm
Radius: 12.54 in 318.60 mm
Circumference: 78.81 in 2,001.82 mm
Revs per Mile: 829.13/mi
Actual Speed: 62.14 mph 100.00 kph

Tire Size 2
235/40R18 Imperial Metric
Section Width: 9.25 in 235.00 mm
Overall Diameter: 25.40 in 645.20 mm
Sidewall Height: 3.70 in 94.00 mm
Radius: 12.70 in 322.60 mm
Circumference: 79.80 in 2,026.96 mm
Revs per Mile: 818.85/mi
Actual Speed: 62.92 mph 101.26 kph
Diameter Variance: 1.26%

ps i don't know who franz is. i have a mate who's dad is called franz but i don't think thats him, he's 68 and not really that in to cars...

[Martin]

I think the S3 has adjustable camber - get it maxed out and you will be surprised at the improvement - very sure footed on turn in (even tolerates braking and turning in)

I'm running 1.75 (1:45) degrees of negative camber on the front of my Octavia - it's fantastic and is not causing any tyre wear problems