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New Wheels and Tyres, wrong size warning!!

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Hi All,

Just a friendly warning to anyone as green as I am!! there are a lot of replica 12 spoke, new A8 style alloy wheels for A8's on sale on ebay at the moment, so I invested in a set of 18's and was ensured they would be delivered fitted with the right size and profile of tyre. Said wheels turned up yesterday, I must say the wheels are drop dead georgeous, but the tyres looked far too thin to me (more like what I'd expect on a 19 or 20 inch rim). So I checked it out and guess what?? 225x40x18's supplied are totally wrong size/profile for the A8 running 18's!! Arghh... so I checked out the correct size using recources on here and they should of course be 245x45x18's!! to keep the correct rolling radius. So I rang up the supplier and had to argue the toss with him for 10 minutes whilst he insisted I was wrong!!, after getting more threatening about product fit for use etc.. and him realising I wasn't a knowledge free zone, said wheels are to be exchanged for a set with the correct size tyres... but these are £30 per tyre more expensive!! I'm OK with that, fair enough, they are still the right price, but it means the initial "deal" advertised isn't as good as it seems! It makes me wonder how many sets they've sold to unsuspecting A8 drivers who are now driving around with their speedo's reading almost 7% fast!!

So the moral of the tale...make sure you specify the exact tyre size you want, don't trust anyone "in the trade" to know jack about anything!! smashfreakB.gif

Regards

Paul N

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I'd always be wary of non-OEM kit. One thing a lot of people also don't consider is the weight of the wheel; the A8 is quite good for low unsprung weight, and a heavy wheel can change the handling significantly.

Well done on noticing and pushing the issue with the supplier!

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As a note to dealers, I enquired with a dealer for 20" rims for my S8, I was looking at Milli F20's. The dealer quoted different size tyres for front and back. Smashing advice on a 4WD.

CB

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Have been informed by a AUDI custom specialist that you can fit larger alloys to the rear of the car without it affecting the car one bit!!!

i.e my wheels are 20x9`s all round,but i could of had 20x10`s on the rear... znaika.gif

Have also seen this on a few pic`s of A8`S and A4`s...

A8Mark..

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[ QUOTE ]

Have been informed by a AUDI custom specialist

[/ QUOTE ]

he's wrong!!

that will completely feck the quattro up, as all of its mechanical settings assume the rolling radius is the same for both front and rear.

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[ QUOTE ]

[ QUOTE ]

Have been informed by a AUDI custom specialist

[/ QUOTE ]

he's wrong!!

that will completely feck the quattro up, as all of its mechanical settings assume the rolling radius is the same for both front and rear.

[/ QUOTE ]

Thats what i thought but only repeating what i was told...

Look here..

Look at the galerie,Audi and A8 section apart from mine and one other the rest have larger rear wheels...

A8Mark...

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Nightmare.You really do need to be careful. Thanks for the warning and hope you get it sorted.

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well they look cool 169144-ok.gif

maybe the rolling radii are identical front/back but the back just have larger offset/thickness then?

that A8 (D3) one looks absolutely feckin awesome. those alloys are gorgeous notworthy.gif

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Make sure these 'experts' know it is a Quattro. Obviously does not matter if it is the fwd version.

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Hmmmmm. aside from static rolling radius you have t0 consider how the tyre deforms under load. With different profile the tyre will deform differently (lower profile [same construction] will deform less, subject to tyre pressures) so whilst on the face of it you get the same radius whilst static it will change under load and the greater the load the greater the difference (when it matters the most). With LSD quattro I would definately stay not only with the same dimensions but the same model (and spec, some tyres vary year to year), manufacturer and size. SEOT.

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Actually, you could have used the following tyre sizes and maintain the correct rolling radius, according to the Audi A8 tyre size tables:

275/35-19

225/60-16

245/50-17

275/40-18

245/45-18

245/40-19

285/30-20

225/55-17

245/35-20

Personally, I'm going for the 19" rims, with 245/40/19s or maybe even 255/40/19 if I'm feeling frisky.

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The audipages A8/S8 Tire Options provides almost all the information you'll need. With a couple of caveats, you can run wider tires in the rear than the front,

- The Torsen can handle a 3% maximum difference in front-to-rear rolling diameter

- Wider rear tires will increase understeer on a nose-heavy car that already has too much understeer.

For example, 245/45-18 up front and 275/40-18 in the rear will work just fine, especially if you install a stiff rear sway bar to reduce the understeer. The car below uses 245/35-19 front and 305/25-19 rear !!

a8000_2000_3.jpg

Randy

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How about 245/45/20 from 245/40/20? Will it raise the ride height on an A8 no matter what suspension settings it's on?

 

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