ABez2k11

OK,
thank you for the info and the input. didn't mean to start anything but I did just ask what size tire would work...and I got my answer.
So I do see that i will have to run 255/35/20 with the 20x8.5.
I would really like to be able to get 20x9 and run a 275/35/20 but Its not gonna be in my price range so I will have to stick with the 8.5.

I do understand and am aware that I may experience/sacrifice a difference in ride quality.
but Is there anything really wrong with 20x8.5 and 255/35/20s?
should I really reconsider or will I be OK using these during the summer?



again,
thanks guys.

MP4.2+6.0

1. have you looked at used OEM in 20's?

2. Can't vouch for ride for 255/35's, but at the end of the day it's not radically different than 275/35's sidewall wise. And the S8 is 265/35, which is only about a .15" sidewall difference from 255/35.

3. Are you on stock suspension, or sport? If the latter and you want smooth ride, you may want to be another notch more cautious.

4. I tried to think of other comparables in a 255/35 -20 like a D3 snow tire fitment or something. None come to mind. And, if its another "cousin" like a C5, C6, Phaeton, etc., without the adaptive air like the D3 (mentioned in my other posts), more difficult to try to draw comparisons.

5. Might help if you back up a step to why 20's instead of 19's if you are holding at 255 given the 8 1/2 wheel? Is it an appearance thing (which is subjective but legitimate)? Or, maybe you want lower profile in general? Both? Or maybe you are locked in on a specific wheel? Also, if this stimulates any thinking, you might look specifically at tire pricing for the relevant 19 and 20" sizing. Both were pricier than 18's, but at least a lot of decent 20's are out there at better price points now with a bigger aftersale tire replacement market.

6. Last, between you and your tire shop and your personal approach, but some (me included) go with wheel width specs for tires, but others don't. If you search, I expect you can find posts on this, including some with much experience, albeit other cars perhaps. What I can note on Audis is they did fit a 255 (40) even on just an 8" wheel on the C5 4.2 as an example, though many would say that should have been a 8.5" in terms of normally recommended specs. I own that car with those wheels and tire fitments and of course it all looks and performs fine--zero tire bulge actually from the wheel. Up to you to connect the dots if you now start at an 8 1/2 wheel; no matter the choice it won't be 100% OEM size matched (either wheel width, tire size or both). Your speedo is meaningfully optimistic if you are starting from 255/45-18s and it will be just as far off at 255/35-20; any change here in greater widths will actually close the error gap some rather than create an independent problem just to tie that checkbox item off.

ABez2k11

well,
what happened was that I was originally going with a 19x8.5 in the style rim that I wanted.
I found them and bought them on eBay, then shortly after I was contacted by the seller and he told me that they did not have that size in there inventory anymore but he could offer me the same wheel in a 20x8.5 for the price of the 19.
I told him I didn't want to go that big because tires would cost too much. The seller directed me to someone who was selling the 255/35/20s for an awesome price.
I started this post to see if I should pull the trigger and send payment.
I m running stock air suspension.
I dont really have a "wheel shop" just a mechanic buddy at a dealership that mounts and balances for free.
I think 20s look good on the Audi A8L, but I just dont want too thin of a side wall either. Is there a size that could give me a better side wall height?
It sounds to me that I should be fine with 255/35/20 but if I could get a better size with a taller sidewall Ill try.


thanks again for your input..

mishar

1. Yes. Used OEM are cheaper, but then why not used aftermarket? They are even cheaper. That’s in the line oranges to oranges, if you follow me. And no. I will not drive buyers car. I will fix it the way I like it and I don’t care if years later I am going to lose a few bucks. But that’s me. I don’t mind if people do not take off plastic wraps from their furniture in order to protect resale value. Watching TV from those is another experience, but a few bucks are a few bucks.
2. That is exactly my suggestion, but you can’t stop comparing things that way. I respect your dedication to OEM stuff, but being OEM is not any kind of scientific or technical proof and you are using it that way.
3. You might be right on this one. It could be just for navigation. By the way, are you a lawyer, or something in that line? You are way more persuasive in that matter than in technics.
4. I am not missing variable dumping, but again those oranges, dumping is same on air and conventional suspension. Springs are different and that difference can’t make up for heavy wheels with stiff rubber. If you have lightweight wheels, big enough to go over your brakes, tires with more of sidewall your drive is going to be better on air as well as on conventional suspension.
Thank you for reminding mi that boards are not always really good source of knowledge. I would add that brochures, magazines, statistics and owner manuals at neither. I prefer university books. I red few of those in order to become MSc. Automotive Engineer. That was like 35 years ago. Since then I added to that some colourful experience, including ability to make distinction between understanding and just piling data.

MP4.2+6.0

to meet typical tire specs. The S8 only goes up slightly on the sidewall height at 265/35 with a meaningfully heavier front end, stiffer antiroll bars and the stiffer shock units. I suggest you make sure to keep the tire pressures up w/ the lower profile, likely around the 40 psi level. When I hear issues about bent wheels or bubbled sidewalls, often the pressures are low (low 30's or less).

MP4.2+6.0

I think we aired most of it out with our perspectives.

the only thing I will run out a little further is on #4 about the adaptive air. Audi does have very good service publications used to train the techs (the SSP's). When Bentley publications offered on line access to their manuals in an earlier time they turned on access to these too, so I got a chance to get into them more. Adaptive air is well explained there, and a variety of other deep subsystems are in various of the other publications. It's not marketing material but rather good technical overviews and details, with lots of illustrations and cutaways. A good number were published around the D3 specifically. Then as to the similarities to conventional suspensions and in turn what the SSP gets into, I was just rotating a set of tires out today and looked up again at the front air shock unit near the upper arms. Look and you will see that thick wire. Trust me, it isn't a ground wire. And that's in addition to the instrumentation (sensors) used with the system and separate and apart from the suspension positioning sensors you find under the car; you'll find those small wires coming off the top of the shock unit under the rear plenum cover behind the motor. The SSP gets into what all of that is doing, and in turn why my perspective is the system really is contributing a lot to the ride quality way beyond what I would otherwise expect with factory very low profile, wide tires by any traditional measure.

mishar

Good. And thank you for pointing to all those wires. It is great system. Not that much greater than conventional with same shocks, but great. Expensive and not nearly as reliable, but has great feature. It levels the car no matter how you load it and you can change height by a press of the button. But even with that great suspension on its best car will ride better with lighter, smaller rims and more of a sidewall on tires. And you wouldn't need to pump them to a solid state in order to avoid bubbled sidewalls and bent rims.

MP4.2+6.0

Back to an earlier question: have you driven the factory 20's? If not, you may be surprised.

williebone

2 great valid points have been made several times over several threads. I find it to be very healthy and even a little heated at times, but good over all since the both of you tend to keep the debate interesting. I love the look of 20s, but some as well as me just do not want to put out the Extra Bucks for a Wheel/Tire Package. If the Original Tire and Wheel Size was 20 to begin with then it makes this Debate Valid. If the OEM Size was 18 to start with then it makes it Valid.

However, there are quite a few of us that have neither Wheel Size and are Smack in the Middle (19s). I think that regardless of Size most tend to gravitate towards the Tire/Wheel Size that they currently have which makes the Wheel Switch Out a No Brainer due to the Cost. I think that if one has the money for a Tire Wheel Package then it should be a Summer/Winter Set-Up (17s-18s) & (19s-20s), but if you are limited to 1 Wheel/Tire Size then converting your current Tire assuming they are New/Good Condition as in my case then sticking with that Size is your only option.

Ultimately people are going to chose Looks over any Data or Arguments that anyone supplies whether supported or unsupported. Based on Looks I can't see 18s except for Winter Set-Up only nor can I see 20s based on the Winter Use here in the MidWest (not enough rubber). The Compromise I think is 19s because with the Right Rubber and Nice Looking Wheel you'll get the Best of Both Worlds if it's your only option. Regardless of Best Ride or not, regardless of a Little Extra Weight or Less, regardless of added Braking, regardless Speedo Calibration +/-, I think that the majority doesn't take the Data/Arguments into consideration.

Net, it will always come down to Affordability, Aesthetics whether New, Used, OEM, Replicas, etc...... In the End the +s & -s are not the Ultimate Factor so we can never steer one way or the other, but instead give all 3 Alternatives based on what can be Afforded! Net, The Compromise is 19s OEM or Not! Just my 2cents and I am one who went the Opposite Direction (Unconventional) in every Aspect and appreciates both sides of the Table, but it wouldn't have mattered because they were the same dimensions as the OEMs and Aluminum (+ or - weight?). Laters,

P.S. The Suspension alots for Softer or Stiffer Rides at the Touch of a Button and @ 40 PSI the Ride is Great!

mishar

You are absolutely right. That's why we have so many divorces.