davey_b

So I've just taken off the 21" alloys that came on the car when I bought it and put on 17" rims that came off an A5 (I put winter tyres on them) and the ride is SO much better. I'm seriously thinking of selling my 21" wheels and getting a smaller size alloy to improve the ride for summer use. Just wondering what people's experiences are of different sizes. Obviously large rims look good but I'm not that fussed about the look and so was thinking of going down to 20" or 19" and was wondering what people have found with regards to ride quality as they've changed rim size.

Any thoughts / experiences much appreciated.

TinyElviss

Glad to hear the ride is even better than before. I did similar, but not as big a move as I went from 20" All Seasons to 19" winter tires.... THe taller sidewall definitely absorbs more road shock and I can barely tell the difference when handling. Of course, at temps hovering around freezing I'm not exactly carving canyons... but on the highway they are great. Just finished a 1000 mile round trip yesterday in fog, snow, rain and dry and the winter tires were up to the task of overtaking at near triple-digit speeds or plowing through large puddles at the speed limit. I may sell/swap my 20's....

Puzz1

I hear ya, but there's nothing like the look of the 20s or 21s vs the smaller tire.

davey_b

Maybe but doesn't really put me up or down. Here's 21 vs 17 I'm not sure it's worth the sacrifice in comfort. Would be interested to see some pics of what 19 inch rims look like

viggense

I definitely prefer the look of the larger wheels; they seem to be more in line with the proportions of the car. I have the 20's and love the ride; most bumps are pretty minor and more audible then felt. I would consider going down to 19" if I could find a design I really liked.

dgbaudiphile

davey_b

I wonder where the sweet spot is? I'm starting to think 20" or 19" is where I'll end up for summer rims but it sounds like 19 gives a better ride than 20 but I guess it'll fit the law of diminishing returns with regards to comfort.

dgbaudiphile

I think you're right. Not sure that 18" will do much more for you than 19". I suspect 19" will have a noticeable difference vs. 20" but then you have to weigh looks vs comfort IMHO. The fact that I'm in an S8 vs an A8 also is an influence for me - purely from an aesthetic standpoint. I'm actually going for more sport than comfort so I'm content with my 20" for winter and 21" for summer. Frankly the 20" are more for protection than comfort. Lots of pot holes in my neck of the woods.

Perky

Is the an changes have to be made in the MMI or an electronics when the tire siZe is changed? Just curious.

MP4.2+6.0

No--beyond very minor like seasonal tire change.

1. Stepping the rim diameter--focus of this discussion--means implicitly that you step the tire aspect ratio. 21 = 35's, 20 = 40's, etc. The ending tire diameter typically falls in the 28.2 to 28.7" or so range for a stock D4. From my own experience with 275/40-20 it puts the diameter near high end of that range and then makes speedo almost dead accurate; it was slightly optimistic on the 275/35-21 S8 OE sizing.

2. Car doesn't even know the difference if you will since all 4 wheels are same diameter relative to each other. Things like ABS (and speedo) just look at revolutions of drivetrain components.

3. As with any wheel change--even seasonal--just click on MMI settings to let the car know to recalibrate the TPMS system for the switch.

Not being discussed directly is that moving from 21 to 20 in OE wheels typically takes out a bunch of unsprung weight Audi pork too. The factory 21's are cast and very heavy. Typical 20" OE's are forged. 7-9 pound delta per corner--depending on which one and maybe a bit 265 vs. 275. Lightening up that whole unsprung assembly helps wheel and suspension better take the beating at margin as well as a bit of drivetrain responsiveness and slight fuel economy benefit. Thus, in stock wheels both the aspect ratio (tire height) change AND the wheel weight reduction can help the overall softer feel, while oddly maybe responsiveness (trading higher aspect ratio for less rotating mass). 21's especially end up being one of those show and not go categories in the stock implementation.

On forged point relative to 20's, factory 19s are cast too IIRC so then the 19's don't pick up the typical weight advantage in stepping down the wheel diameter. 19" ride will soften marginally with a bigger aspect ratio tire still, but 20-19 won't have both the tire height and weight reduction advantage like a 21-20 step. Again, all assumes factory wheels and choices--lots of aftermarket stuff with quality from commodity low end to big bucks and a variety of manufacturing processes.