View Full Version : whats the advantage of biger wheels, from 16 to 18 for example


alezome
12-09-2006, 12:14 AM

iProDrive
12-09-2006, 12:36 AM
I am considering going 18" for summer 07'. My cons are its a bumpy-er ride and the pot holes will be my worst enemy.

16" to 18" would also improve the cars looks IMHO.

Try a <a href="http://search.audiworld.com/">AW Search</a> in the C5 A6 forum for "bigger rims".

4Driver4
12-09-2006, 04:13 AM
True a larger wheel can sometimes give better road feel and enhance handling, but larger wheels are almost always heavier wheels. Heavier wheels add unsprung weight and unsprung weight degrades accelleration, braking and handling.

Like everything else, wheel size is compromise; you need to find a wheel that is large and wide enough to maximize handling, but light enough not to destroy handing. The other problem is that lighter and stronger are usually more expensive, so most larger diameter wheels tend to be heavier.

IMHO, a light, strong 17 x 8 is the optimal size for the C5. People go larger for a cool look and damage the drivability. Then they install there winter tires on stock wheels and "rediscover" their cars.

Kris Hansen
12-09-2006, 04:55 AM
Because the weight of the wheel is farther out from the hub. I noticed a difference going from my 17s to my 16 steelies. =)

Murph
12-09-2006, 05:09 AM
The larger the wheel as 4Driver4 stated below the more you have to spend to get a lighter one. You will also pay more for tires and have much shorter tread life. You also have a much higher risk of bending them at 18+. I agree that a good 17 x 8 with 235/45/17's is the best all round setup.

Press
12-09-2006, 05:24 AM
i have two sets of 17's and one set of 18's and they serve different purposes.....one set of 17's are snows, one set i use on the track, and my 18's are oem rs6 wheels that have summer only rubber on them....weight is important, but these car are heavy to begin with so a few extra pounds make little difference on the street....if you're going to track the car then that's a different story....8^)

EdCz
12-09-2006, 07:09 AM
crisper turn in due to smaller side walls and a generally a wider "footprint".

Cargasm2.7
12-09-2006, 07:23 AM
turn in.

The cons are obvious....firmer ride, more $$$, and more prone to wheel damage.


Recently, the group mentallity on this board has convinced themselves that 17's are the way to go, keep in mind they are old farts....loveable, but old farts nonetheless. : )

Press
12-09-2006, 07:35 AM
btw....i like my 18's....

Cargasm2.7
12-09-2006, 07:47 AM
money were no object, 18's would be better for the track. However, if I end up buying track wheels, they too will be 17's. The cost factor and more readily available light weight wheels makes it a no-brainer.

SouthboroAudiGuy
12-09-2006, 08:02 AM
That said, the points Cargasm makes are good ones.

The "more road feel" point is a plus but, when carried to extreme with really big wheels, quickly turns into a ride that is harsh.

"Larger contact patch" is a function of width, not diameter. As such, a 17x8" wheel will give you the same advantage here as an 18x8" wheel. Going wider is definitely an important part of your upgrade, no matter which diameter you choose.

"Better looks" is a subjective thing. I am not a fan of the rubber band look so I think 19" wheels on a C5 looks too extreme. There are some wheels that pull this off better than others, but at 19" I think it's tough to not subtract from the understated elegance of the C5.

The improvement I most noticed when I upgrade my wheels (from 16x7 to 17x8) was improved turn in. This is the responsiveness of the car to input from the steering wheel. The lower profile of the tires means that there is less tire flex when you turn the wheel. "More responsive" is the bottom line here.

If you're go 18" or greater, be prepared to spend some big bucks. The only way of offsetting the increased weight and higher risk of a bent rim is to buy GOOD wheels. Strong <i>and</i> light costs more. You'll also have to pay more for lower profile tires so that also drives up cost as you go up in size.

Final note... lower profile tires also require more vigilant attention to maintaining proper tire pressure. A very low profile tire that does not have the right air in it is MUCH more likely to get bent should you hit a good pothole. Something to keep in mind before AND after you make your decision.

Good luck!

Press
12-09-2006, 08:47 AM

April
12-09-2006, 08:51 AM
the result of shorter sidewalls, not the larger wheel itself. The best and detailed feedback comes from the lightest wheels and tires, since they offer the least inertia to filter out feedback. A heavier wheel/tire combo damps feedback, so only the larger inputs are felt.

Then there is the inertia when steering the wheel (sure the larger contact will help once it's turned, but initial turn-in is slower), the engine power required accelerate the heavier wheel, the brakes that must halt the wheel, and the suspension that must control the bouncing of the wheel. All are degraded by heavier wheels/tires. It's like you wearing heavy duty hiking boots vs running shoes.

Then again it's not just the weight of the wheel out on the rim, but tires aren't light either, so that larger tire is usually heavier as well. Then there is the expense of those tires.

BoneDaddy
12-09-2006, 08:54 AM
and I'm 25 years old going on 12, or 50, depending on the moment...haha. and by good larger wheels costing more, we're talking in the 400+ per wheel price range, without tires.

Cargasm2.7
12-09-2006, 08:58 AM
Whether or not the ride can become "harsh" with 18's will depend more on the suspension set-up than the wheel size. If someone finds 18's on ANY of the stock suspensions to be unbearable, the "old fart" theory becomes solidified (health issues aside)and the next stop should be the local Lincoln or Lexus dealer.

As for the "contact patch", again, the question was about going from 16's to 18's. It would be very tough to find a 16" wheel for this car w/a 8" width. In fact, I don't ever recall seeing one.

When it comes to the aesthetics, nobody can argue one way or another, it is simply too subjective. I feel an 18" provides plenty of sidewall and is far from a "rubber band" look, but that's nothing more than my opinion.

4Driver4
12-09-2006, 09:05 AM

Just Me
12-09-2006, 09:20 AM
I wonder how many people with 18s drive around with a perpetual shimmy -- and no steering feel. I see enough ebnt ones!

Grant

Just Me
12-09-2006, 09:21 AM

Just Me
12-09-2006, 09:25 AM
Large calipers simply require larger rims.

Ideally, I like the balance of 17 x 8 on my S6. But for winter, and often for lousy NJ roads, my 16 x 8 rims with slightly oversized tirees gives me lots of advantages:

- better ride
- pothole resistance
- cheaper tires

Keep in mind also that many people who go "=1" go from soft all-season tires (such as audi ships) to high performance tires. Of course they say "wow". Put the same V or W rated tires on your 16s and you might say "wow" too.

Nothing against larger wheels, but they probably wont stay round for long, if you live where I do, and drive where I do.

Grant

SouthboroAudiGuy
12-09-2006, 09:27 AM
I took that to mean that the inquiry was about plus sizing in general, not just +2.

I think we're in agreement on the main points here...

As I also noted, suspension choice certainly affects ride quality as much or more than wheel size. That said, I've had plenty of conversations with performance minded people who own 18s and say be happy to have a softer ride. This doesn't mean that they find the ride of an 18 inch wheel <i>"unbearable"</i> - merely that they see the gentler ride of a 17 inch wheel as <i>one</i> of multiple advantages (lower weight, performance, resistance to damage, etc.). Saying that these people should be sent to a Lincoln dealership is just silly.

Agreed that upgrading from a 16x7" wheel to a 16x8" might not be the best way to spend your money, but I think it's important to note that the benefits of a wider patch aren't necessarily tired to diameter. Lots of happy 17x8" people out there.

Finally, I totally agree that the aestetic aspect of the dialog "is simply too subjective" to ever be settled. To each his/her own.

SouthboroAudiGuy
12-09-2006, 09:39 AM
...but doesn't the stiffer sidewall of a lower profile tire offset this when going up in width AND diameter? When people upgrade their wheels, they tend to increase both.

I certainly notice improved turn-in with my summer wheels (17x8 BBS RKs with 235/45 tires) as compared to my winter wheels (16x7 OEM 2001 sport wheels and 215/55 tires). It looks like the lower weight of the wheels and stiffer sidewall of the low profile tires really do make up for any loss of turn-in performance that the wider patch may cause.

R2.7TA6
12-09-2006, 10:22 AM
nows where my cane so I can whip this boy.

April
12-09-2006, 11:43 AM
even if the car ultimately has more grip once turned. The difference between being fast overall and being quick on the draw:-)

Try paying attention to how quickly the steering wheel responds and with how much resistance, when you run lighter wheels. Sometimes people think the quicker turning of the steering wheel means less feedback, but if all other things are equal, the shorter sidewall and lighter wheel will always respond the quickest. If you have a light touch on the wheel instead of man-handling or expecting lots of kickback, you can learn all kinds of subtle things that might escape those who use the method of brute force. After all, the fastest driver on the track is usually the one who turns the steering wheel the least and the most smoothly in corners.

Just Me
12-09-2006, 11:50 AM
how much of that "feel for the road" was the +1 change and how much was the undoubted upgrade to more performance oriented tires.

Both contribute - no disagreement on that point.

But for my curiosity - what was the size, make, model and speed rating of:

- the original set of tyres
- the repalcement set

Grant

iProDrive
12-09-2006, 12:03 PM
It is just your own perception. "butt dyno"

Went from: [Pre-Spring '06]

16" Audi Wine Glass Rims
205/55/16 "Big O" Touring All Season Tires

-to-

[Summer '06 to Dec '06]
17" Audi Gunmetal Five Spoke Rims [See Sig]
225/45/17 Kumho ECSTA ASX High Performance All Season Tire

I am actually going to see how this winter goes with DECENT winter tires:

16" Audi Wine Glass Rims
205/55ZR-16 Avon Tech M550 A/S

SouthboroAudiGuy
12-09-2006, 12:04 PM
I have the somewhat unusual situation of my larger wheels being lighter than my smaller ones. My 17x8 BBS RKs weigh less than my 16x7 OEM sport wheels because they are a particularly light design. So, when I switch to "summer mode" it's a really nice improvement -- better performance, better steering responsiveness, better road feel, and minimal loss of ride comfort.

I'm confused though...

In your earlier post, you say "the larger contact will help once it's turned, but initial turn-in is slower." In your later post, you say "the wider patch helps turn-in." There are logical arguments for either viewpoint... The former might be true given the reduced contact area that needs to be turned -- the extreme example being the responsiveness of a bicycle tire. The latter might be true given the additional traction cutting into the turn given the wider patch. Which are you saying is true?

April
12-09-2006, 12:19 PM
based and and rotational based inertia (more mass is usually on the outer rim), to get both front wheels to turn in the desired direction. That's one action - made by the driver. Once the wheels are turned, the grip at contact patches determine how faithfully the tires can deliver on the driver's request. Driver's input, car's reaction. Both could be called initial turn-in. One a request, the other the actual delivery.

I wasn't clear. Sorry.

April
12-09-2006, 12:24 PM
in the country. Bent rims and bubbled sidewalls are just a fact of life if you go too large here. 17 is my limit for every day comfort. For cars that are designed from the factory to roll with 18s, it's another matter.

SouthboroAudiGuy
12-09-2006, 12:25 PM

Just Me
12-10-2006, 04:25 AM
you see the diff right there

..Although you did not specify the speed rating of each - which correlates very well with sidewall stiffness, and thus steering response.

Dont think of this as picky - it probably is MORE signficant than the size change! That's my point.

Grant

Just Me
12-10-2006, 06:02 AM
"Thanks for the data" - see text for comments.

SouthboroAudiGuy
12-11-2006, 05:01 AM