2001 A8L vs A8 wheel sizes

[gworrel]

I have been looking for winter wheels for my 2001 A8L and was surprised to find today that many wheels that will fit the A8 will not fit the A8L. At least that is what the Tirerack web site suggests. When I search on their web site for 17" wheels for the 2001 A8L I get only 15 choices, but the A8 shows 52 options. I asked on the wheel and tire forum and Gary@tirerack.com said he thinks it is a brake clearance issue. When I check 18" wheels, the A8 has 52 options, the S8 has 29 options, and the A8L has only 27 choices. This does not seem right. Is it possible a wheel that fits on the S8 would not fit on the A8L? I want to use the Blizzak WS-50 which is not offered in anything larger than 17" sizes. I have been looking at wheels on eBay and elsewhere but now I am concerned about buying any wheel not specifically tested on the A8L. Greg Worrel

[chucklane]

That odd very odd. The S8 has the biggest breaks out of the 3 and i believe the A8L's are a bit bit bigger than the A8's there is no reason why the 18's on the A8 shouldnt fit the A8L. Hec the standard wheels for the A8L where only 17's. Furthermore you could even get 16's in Europe i believe.

[PaulW]

Just seems that the tirerack.com is not correct.

17" wheels with et 48 to 35 should work just fine. Heck, I have my Porsche brakes under the stock 17" wheels no problem.

pw

[gworrel]

I don't know if it would make a difference in wheel fitment, but the brake discs are larger on the A8L.

From the Audiworld Tech historical guide for 2001:
Front, size and type:
A8: 12.3 in. (312 x 25 mm) - Ventilated disc A8L: 12.7 in. (323 x 30 mm) - Ventilated disc
Rear, size and type:
A8: 9.6 in. (245 x 10 mm) - Solid disc
A8L: 10.6 in. (269 x 22 mm) - Solid disc

The standard wheel was 7Jx16in for both A8 and A8L

• http://www.audiworld.com/model/a8/01/specs.shtml

[PaulW]

But my front brakes are 332 x 32mm and they still fit, have huge calipers too. I don't want to say any 17" wheel will fit, but I'll bet a paycheck that anything with a offset of 48 to 35 will.

Ebay always has a lot of A4 and A6 take offs for sale, but you'll need different size tires....but you already are getting new ones.

pw

[chucklane]

[CA_A8]

...and that info from an 'official' spec sheet? Have a look at your rear discs - they look solidly made, but also well ventilated!

[ryoung]

I can understand why a wheel that would fit the A8/A8L would not fit the S8, but I can't understand the difference between the A8 and A8L for a 17" wheel.

A8 - 12.3" (312 mm) rotor with 16" wheel and sliding caliper
A8L - 12.7" (323 mm) rotor with 16" wheel and sliding caliper
S8 - 13.6" (345 mm rotor) with 18" wheel and fixed caliper
My S8 - 14" (355 mm) rotor with 18" wheel and fixed caliper

First consider wheel rim and caliper interference resulting from rotor diameter changes. With one caveat, I could fit a 17" Avus wheel over my Alcon calipers on the 14" rotor. It would be VERY close, but it would fit. The caveat: It's so close that a stick-on wheel weight would hit the caliper if they're in the same plane. If I could (barely) fit a 17" wheel over a 14" rotor, I can't imagine that an A8L caliper on a 12.7" rotor would hit the rim.

Then there's the problem of caliper - spoke interference, which is the reason for the difference between the A8/A8L and the S8 wheel options. With the sliding caliper of the A8/A8L, the single piston is located on the inside of the rotor and away from the wheel. With fixed calipers, you have opposing pistons on both sides of the rotor. The difference is apparent in these pics.




The result is that even if there's no problem with rotor diameter, the "thicker" outside portion of a fixed caliper may hit the spokes of a wheel that would clear the A8/A8L's sliding caliper. I suppose it's conceivable that moving a sliding caliper out 0.2" on the A8L could cause a problem with a wheel's spokes, but this seems extremely unlikely.

My conclusion: Tirerack is in error. The 17" A8 wheels will fit an A8L.

[PaulW]

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