ITotem

Getting smaller wheels will probably make your ride quieter because you have mode sidewall to absorb bumps and road noise. However, the big noise factor is really how soft is the rubber in your tires. If you make a Google search for quiet tires, you'll probably find that you can purchase alternative brands/models to make it quieter.

Example: https://www.tirereview.com/sound-of-...-a-quiet-ride/

You may also read reviews like this: https://tirereviewsandmore.com/top-10-quietest-tires/

My 2018 Audi A6 has the Pirelli P-Zeros. My fiance thought it was louder than my old 1998 Lexus ES 300 that had softer Michelin 16 inches tires. When I made some research, I believe the Continentals and the Michelin are usually considered quieter (don't remember which model)

DB22

Another consideration is the aging of tires. My PZeros got very loud with age as did my Yokohama’s but Pirelli P7’s not so much and my Scopion Verdes were good too. Nobody seems to rate the aging noise issue.

Fahrer

If you want a smoother quieter ride it does not make sense to convert to a non-sport suspension. However, one should make sure that the tire pressures are correct. As previously mentioned check the owner's manual for the correct cold tire pressures for your car/wheels/tires. The next thing to consider is the tires and wheels. Moving from 20 inch to 18 inch wheels will definitely improve the ride. Ultimate grip is not affected that much, just initial turn-in at speed. The smaller wheels and tires last longer, are cheaper to replace and are not as easily damaged. Finally, a move from summer ultra high performance tires to all-season tires will result in a smoother, quieter ride and they will last longer as well. Larger rims are for styling mainly. Many folks do not realize that the need to improve pedestrian safety has resulted i high hood lines and therefore smaller side windows and more sheet metal from the side view. The larger wheels help break up the slab-sided look from the side view. Engineers prefer smaller rims. Stylists prefer larger rims. Larger rims are more suitable for high speed driving on smooth roads like on German Autobahns ( 100+ mph)

DanfZX14

I concur. My PZeros got obnoxiously loud at the end of their useful life so much so people were asking if I had snow tires on the car

snowchaser

Funny, as I was at the dealer today and spoke to a sales rep and said: "Why the hell do you order all of your A6'd and A7's with sport suspension and 20-inch wheels?" His response was "that is what sells best and he loves a stiff ride". I looked a long time to find a used A6 TDI without sport suspension. There are very few out there. I think sport suspension in the US is pure stupidity. I drive in Europe at least 3 times per year. Most dealers are showing cars with smaller wheels and nonsport. To answer your question, the 18-inch wheels will help you. I found the Continental extreme contact tires very compliant on bumps and great in the rain. In fact, I learned that in Europe the A6 was sold with 17's (Not available in the States). I found a pair of 17's off an A4 and use them on my A6 in the winter. They work great. The bigger wheels as you mentioned will handle better, but are twitchy also. I personally don't like every fraction of a move on my wheel to result in input on the road. I am not on the track. Get the 18's and Continentals and you will be happier. Ditch the sport suspension and lowering. Makes 0 sense for our market.

superswiss

When I hear somebody call an A6 harsh, I have to wonder if they are off-roading it or something . There's nothing wrong with a sport suspension or 20s, but everybody has different expectations. I daily an RS5 with 20s and a much firmer suspension than anything you can get on an A6, and I find the ride comfortable unless I drive on some really terrible roads that should have been repaved 20 years ago. I avoid them or drive a little slower until I get back on proper pavement. A lot of this of course depends specifically on the quality of roads in your area. Fortunately, a lot of roads and highways around here have been repaved in the last 10 years and California is also one of the states that uses rubberized asphalt. This type of pavement drastically reduces road noise. However, I do prefer a firmer ride that gives me feedback about the road. I dislike floaty suspensions that feel like you are driving on marshmallows.

A few thoughts on what you can do. First off is using the proper tire pressure as has been mentioned already. The USA is absolutely terrible with driver education and as a consequence, nobody really understands the significance of using the right tire pressure and regularly checking it as changes in temperature will change the pressure. The DOT has gone so far as to dumb down the recommended tire pressure sticker in the door jamb to only show the max load recommended tire pressure, because poor Americans could get confused by all those numbers. In the ROW, this sticker shows various different tire pressures based on load, speed, number of passengers and type of tires. You can find this extra information in the owner's manual. What you are looking for is the normal load recommended tire pressure, which you should be using anytime other than when you load up the car full of passengers and cargo.

Reducing the size of the tires certainly makes a difference and especially if your roads are full of potholes, getting more sidewall between the road and the wheel can avoid a bent rim. But also the tire itself can make a difference. I would say stay away from Pirelli, especially the P Zero. It's not a very comfortable riding tire and it gets noisy about half way through the lifecycle. If you value comfort and quietness, you wanna look for a touring tire. There are many different types of tires. Summer performance tires will ride firmer, handle better, and be more noisy. All-season tires could be an option, but even there you'll find different subcategories. Choosing the right type of tire for the driving you do and the expectations you have is key. What's coming from the factory is not necessarily suitable to your needs and wants. You'll have to do your homework. Tirerack is a good source of information. They compare various tires and have grading schemes. First enter your make and model and see what tires are available for your car and then compare them and pick something that rates high in the area such as ride comfort and noise.

Jennifer L Allen

what size did you buy

newmoon

Michelin Premier A/S 245/45R18 100V XL

shadowcar

Had a 2015 and now a 2018 A6 3.0 both with Continental tires on 18" wheels and both were very quiet with a comfortable ride. I test drove one with 20" wheels and wasn't happy with the ride over New England roads.

nhdoc

And for what it is worth I don't think you would call the standard suspension on the A6 "spongy" or "floaty". It is a typical European ride and more befitting a luxury sedan than the hard sport suspension, in my opinion. Audi (and other car makers) like to sell the sport suspension and larger wheels because it's an upsell "option" and very profitable. Think about it, they charge a couple of grand for some stiffer, shorter springs and wheels that don't cost any more to make than the smaller ones. Maybe the tires cost them an extra $200 for the set. My guess is the profit margin on the optional wheels/suspension package is around 90%, so of course most cars have it.