JohnHugill

Good afternoon, all. My A8 came with the miserable Pirellis, that go zoom zoom zoom after a while (my previous A4 had the same issue). I had replaced the Pirellis in the A4 with Michelin Pilot Autosports, and it drove fantastic. Anyway, my A8 comes with 265-40R-20-104H and I'd like to buy these tires from Costco as I had done with the A4. Costco does not sell the Michelin Pilot in this size. The closest they can come in the Michelin Pilot is 255-40R-20. Costco does sell the 265-40R-20 from a different manufacturer, but I was so pleased before with the Michelins that I'd like to go with them again.
Would anyone know if I can use the 255-40R-20 tire from Costco? Thanks, all.

Baloo588

You can use the 255/40R20 tires. I am putting on the 255/40R20 Michelin Pilot Sport AS Plus n-spec from tirerack. I prefer not to EVER take any of my luxury cars to costco. They are terrible at mounting the tires and have really cheap old school dynamic wheel balancers and the ride that I get regardless of the tire is crap. Not smooth at speed with vibrations etc. I would buy the tires separately and take them to your reputable Audi dealership and DO road force balancing. There are alot of people on this board who will say its the best especially for the sensitive A8 suspension. Road force balancing in my own experience keeps the best balance and makes sure the tire is mounted at optimal position on the rim before dynamically balancing them. My tires last much longer and my cars ride glass smooth with road force balancing over standard dynamic balancing.

Also costs doesnt routinely calibrate their balancers so its always off at times and I prefer the routine calibration and higher tolerance road force machines that the dealers have. FYI.

MP4.2+6.0

Is your car a lease? If so, need to stick to the OE tire size or get dinged on the return.

Otherwise, I prefer the 275/40-20 size for D4, which is all of a bit more rubber, a bit more sidewall for ride and wheel protection, a bit more wheel well fill out, and a very accurate speedo. But, still needs to tie to your choice in tires if possible. There are a lot more 275 choices than what is basically an Audi orphan 265 size.

LexusLSguy

Do Audi dealers actually have and use road-force balancing? If you are saving a good amount at Costco you could always have another shop road-force balance after the install. I also experienced how sensitive these car are to balance. I missed some snow on the inside of rim during from our last big snow. Boy was she unhappy when I jumped on the highway... lol. Had to pull over and clean it off immediately.

Baloo588

True but I rather do it right first time and make sure all 4 tires are in spec or I get them replaced on spot from tirerack. It's not about saving money but spending it right the first time and getting perfect assemblyou without out of round tires that I usually find once or twice a year on my 4 cars. Costco has no road force machines and they give u a hard time if you come back to them after getting road force done elsewhere and one tire is bad. It's total waste of my time. Yeah snow in rim is annoying I've had that happen before.

I didn't say you have to use audi dealer for road force but any independent mechanic that has expertise in it. I have another independent mechanic near my house that does it for my cars also and he's really good. It's tirerack top installer.

JohnHugill

Gentlemen, good morning all. Thanks for all your input. I have a lot to think about. I learned a lot, and thanks to all for sharing. John

Baloo588

ANytime! And if you want more options, go to www.tirerack.com and look up both the 255/40R20 tires and 275/40R20 tires.

The problem I had with the 255/45 R20 that i put on the 20s last year was that my MPG dropped by 2-3 mpg or so from 27 mpg to 24-25 mph at 80 mph and I do mostly highways so my cruising range dropped by 60 miles which was significant compared to my standard 255/45R19 tires so when I did tire calculation, 255/40R20 is more appropriate size to keep within spec.

I know 275/40R20 could be another possibility but it was still a bit bigger then I want and close to the thicker 255/45R20 tire and I didnt want to compromise my MPG and speedo. MP4.2 did recommend 275/40R20 last year which I should of gone with in the first place since standard tire is 265/40R20. However the Michelins pilot sport as plus n-spec comes in 255/40R20 and I preferred to get a good Michelin with n-spec rated (designed for porsche). MP4.2, did you notice any drop in your overall highway MPG Or overall cruising range with 275/40R20 over the standard 265/40R20? I know you have the S8.

LexusLSguy

Keep in mind running a tire that is not the exact size the car is calibrated to will not only cause your speedometer to be off but also how the vehicle calculates mileage. Even going from a 265/40/20 to a 255/40/20 is a 1.12% error. Not much but over the course of 50k miles your vehicle would read 560 miles more then actual. When traveling at 80 mph you will actually be driving 81 mph. Again, not a big difference but something to consider.

Edit: If you wanted change rim size you can obviously get very close to original spec. 265/40/20 to a 265/45/19 is only .15% off. If you went to a 285 you would be better off with a 35 sidewall but the sacrifice is that a tire this size is like a rock. You can bend rims pretty easily. Personally, a 45 sidewall is bad enough when it comes to crappy roads in the northeast.

SWelsch

Just put the OEM size Pirellis on with the noise cancellation feature.Got 32k miles on the original set.
Significant reduction in noise, nice all around performer. Leased car

dwboston

I went with Conti DWS 06 275/40/20 when I swapped tires recently on my 2015 NWB A8. I was not a fan of the stock Pirellis, as they felt floaty at speed on the highway. Speedometer is spot on with the new tires - verified with GPS. MPG seems a bit better, though that was with an unusually warm stretch between February and early March here in the Northeast.

I would have preferred Michelins as well. I had a set of Michelin Premier A/S on my A6 that I loved, and ran Michelins on my Acuras prior to that.