2016 S5 - Downsizing to 18 from 20 wheels

[Advaitha]

Hi,
Apologies if this has been already asked, but I couldnt find it in search regarding downsizing on this model. I recently purchased a 2016 S5 CPO which came with upgraded 20" Continental tires (265/30/ZR20). I feel the ride is a bit rough, and reading through many threads here, I am thinking the cause might be the 20" tires.
Out of curiosity, went to discount tire and inquired about 18" wheels. They are recommending 18 * 8.5 W with Michelin Pilot Sport 3s. When quesitoned about the 8.5 wide wheel, they say it is to clear the large breaks. Looking elsewhere (tirerack, oemwheels etc) the default recommendation seems to be 18*8 or 19*8.5.
Does anyone know if downsizing would help in a more comfortable ride? I am coming from a 2015 Q50S, which was extremely rough and noisy. What size tires would you guys recommend to downsize? 8 or 8.5 wide?

[SLU_S5]

I have 18x8.5 et29 OEM S5 wheels that I use in the winter. Cleared my stock brakes without any problem, and clear my RS5 brakes with a 20mm spacer (probably only needs 15mm)

18x8 should also work just fine. The main thing to be aware of is the offset.

I also find that 18s are the most comfortable wheel tire option since you have a lot more rubber between the wheel and the road. I love the look of 20s but the ride is fairly harsh... I've found that 19s are a fair compromise between looks, and handling feel/comfort.

[JoshDub]

First of all, the width of the wheel does not determine if the wheel will clear the brakes. The diameter and offset do.

Secondly, the wheels discount tire sells are probably going to look like ass.

Third, the width of the wheel on roughly determines the size of the tire. You can fit a wide range of tire widths on a single wheel width. The two sizes in 18" that have the same rolling diameter as your stock wheels are 265/40/18 and 235/45/18. To soften up the ride, you need a larger sidewall, which is the middle number.

I would recommend you trade for anothers s5 19" setup or a stock a5 18" setup.

If you think the sq5 was rough I don't think you are going to be happy with any of these outcomes.

[shyamvenky]

On my A5, I have 19" stock wheels with Michelins and I'm quite comfortable with it.
Initially I did have concerns, but after driving for a while, I'm ok with it.
I was also initially considering moving down to 18", but the 19" wheels are an excellent compromise.
If you're in the Bellevue, WA area - then I understand your concerns with the rough concrete roads out here

Just lookup for the stock config in your car's manual or online.
If you're not looking to add sporty/aggressive or lightened wheels, I would just stick to stock options.

Cosmetically 18" wheels might look funny on an S5/A5, though that's just my opinion
As Josh said, 18" will give a much improved ride when compared to 20" wheels, and much more tire options.
Check local craigslist posts for OEM wheels+tires.

Brand, 'flavor' of tires also contributes to noise. Again, for the Bellevue, WA area (PNW) I'd recommend All-Season tires. Pilot Sport 3 is Summer Tire, correct?
Here's a good summary. I'm up for a tire set change and I'm opting for the Michelin AS3+ (Costco has a nice deal until the end of the week methinks)
https://www.tirerack.com/tires/surve...35&diameter=19

[Drew0u812]

Brand, 'flavor' of tires also contributes to noise. Again, for the Bellevue, WA area (PNW) I'd recommend All-Season tires. Pilot Sport 3 is Summer Tire, correct?
Here's a good summary. I'm up for a tire set change and I'm opting for the Michelin AS3+ (Costco has a nice deal until the end of the week methinks)
https://www.tirerack.com/tires/surve...35&diameter=19

I currently have about 2500 miles on the Michelin Pilot Sport A/S 3+, and I can say that they are very nice, they have that "am kinda good at everything" feel....good in rain, light snow, rides quiet, good handling.

[Advaitha]

Thank you everyone. I went ahead and purchased the Drag Wheels DR-37 (they confirmed it will take the Audi center cap) with 255/40/18 Michelin Pilot Sport A/S 3 Plus. They will put them on the car this friday and I will edit this post with my thoughts on how the drive is. Again, thanks everyone for your input. They helped me quite a bit.