Scott in Cincy

Ok, I have a couple of questions that I never really gave much thought to until now. Being that quattro is AWD, it stands to reason that you would have equal tire wear front to back, correct?

Or by virtue that the fronts are also steering, would you be wearing those most quickly?


Question 2: If you were putting 20" wheels on a 2005 A8, what size tire would you use? I bought a set of wheels through a fellow board member, and they are A8 W12 wheels. If you look at Tire Rack, they say 255/35/20's if you look under the 4.2. If you look under W12's they say 275/35/20's. I'd rather not have any speedometer error if I can help it (I have enough problems with the state troopers). So, which way do you go?

Thanks,
Scott

V8growler

have higher braking forces on the front too.

I have 275/35/20 tires on my 4.2 (Audi fitted option) so these are what you should go for I guess. They work for me.

MP4.2+6.0

The best metric is the rolling circumference. Some tire co's publish this, but it is hard to find; sometimes you compute it from a loaded radius spec. that they quote. Failing that, just line up the diameters as an approximation. Tire Rack's site has that for many but all tires. A8's are quite large tires at around 27". Thus look up your current tire and size as the guide for diameter.

For reference, I have a copy of a German test of the W12 where they showed a fair amount of speedo error--on the HIGH side as expected. The tested car had 255/45 18's (Bridgestone RE 040's). Indicated 100 kph (62 mph) was actually 95 kph, 130 kph indicated (81 mph) was 123 kph actual. Thus about a 5% error--that's a lot. Thus upping the diameter and therefore circumference by a few percent as I think you would with the 275's would actually reduce the error. Yeah, they might have tweaked the electronics a bit for tire size between W12's and 4.2's, but the basic principle of it usually reads optimisticly still holds. (test it w/ a handheld GPS to nail it exactly) Most speedo's are several percent high to begin with. Virtually never are they dead on or low, because manufacturers pay fines if they are found to read low and are caught, but not if they are found to read high.

For real world, by the way the 275/35's definitely look cool. I would be hesitant to go to a 35 in 255 because that's even less rubber between rim and road.

geordie

correct some of the speedo error which does exist.

Scott in Cincy

I have summer Contis on it now, being that it came from Houston. BUT, that's not really practical in Ohio.

I don't care horribly about treadwear, I think 30k miles is about all you can expect on an AWD car. BUT, I do care about tread *noise*...I hate tires that get racous as they age.

I like Michelins, but obviously, Michelin likes Michelin too. They demand a high premium that sometimes isn't warranted.

Any suggestions?

MP4.2+6.0

A6 4.2: Pirelli PZero Nero M + S. So far a high quality tire; quiet, handles, etc. Well rated. Available in 275/35 20 and has a 102/XL load rating--A8's being pretty heavy. My likely next tire if I use an all season--SF Bay Area w/ Tahoe trips. Michelin may have the better tread pattern for snow, but you would have to check reviews on snow/crud performance. On the other hand, 275 isn't really the size for snow; 255 is already a lot.

Scott in Cincy

it's usually just slushy crap. My wife's X5 4.8is with Michelin Latitudes does just fine with M+S capability, and those are 315's in the back (yikes!).

Most tires in that size seem to go for the 280ish bux range. Cept for Michelins which are in the 340 range.

geordie

Michelin Pilot Sport A/S 275/35 20

tjf

18's. Very quiet. Good grip. Good ride. Good price. I had a bit of vibration on them at first, so the tire shop just remounted a couple of them yesterday. We'll see how that works out. They've gotten very good reviews from Tire rack customers.