2016 A6 original equipment 18" wheels
08-27-2015, 07:40 AM
#11
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I've never heard that reducing wheel/tire weight will increase ride quality. Are you sure that is the case? I don't see the connection. Increasing the tire sidewall is the generally the way to improve ride quality ("minus sizing"). My 17" wheels with snow tires are a lot smoother than the 19s.
08-27-2015, 07:44 AM
#12
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08-27-2015, 11:04 AM
#13
I've never heard that reducing wheel/tire weight will increase ride quality. Are you sure that is the case? I don't see the connection. Increasing the tire sidewall is the generally the way to improve ride quality ("minus sizing"). My 17" wheels with snow tires are a lot smoother than the 19s.
08-27-2015, 11:27 AM
#14
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Cars can handle better and ride better with lighter tire/wheel combinations as it is easier for the suspension to control the wheels. In addition, ABS can work a bit better as the control of rotational momentum is easier. Winter tires ride more comfortable as they often have larger sidewalls, softer rubber and more tread. If your 17 inch wheels were lighter they would handle and ride even (slightly) better. Larger rims are generally used for looks mainly. Yes, less sidewall and more wheel will improve transient response but not affect ultimate adhesion that much. My 911 came with 19 inch OEM forged wheels for styling purposes but for track use, 18 inch wheels are always used on these cars.
Think of a wheel and tire assembly as a pendulum, albeit in the vertical direction, rather than the usual horizontal. As the assembly moves up and down, the greater mass is more challenging to restrain and when it reaches the full jounce or rebound, it hits with more force (mass x velocity). That impact is a cause of ride deterioration. Further, because of the greater mass, more force is required by hitting a road imperfection to get the assembly to deflect on the suspension, so the assembly is more likely to "crash" into a bump than deflect to ride over it, as compared to a lower mass assembly.
08-27-2015, 02:29 PM
#15
I remember reading that reducing unsprung weight was a goal for improving handling and ride from my earliest teen days in Motor Trend, Sports Car Graphic and other magazines. I got my first subscription to a car mag back in the late 1950's and have been into cars ever since. The concept of low unsprung weight is like "better handling 101."
08-28-2015, 11:23 AM
#16
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I've never heard that reducing wheel/tire weight will increase ride quality. Are you sure that is the case? I don't see the connection. Increasing the tire sidewall is the generally the way to improve ride quality ("minus sizing"). My 17" wheels with snow tires are a lot smoother than the 19s.
Imagine holding a 25 lbs dumbbell in one hand in front of your body, and imagine someone pushing it directly toward you. This is analogous to when your wheel goes over a bump in the road and the wheel is pushed upward. Your body is the vehicle, and the dumbbell is the wheel. Your elbow bends as the dumbbell comes toward you and then your arm resists the dumbbell and returns it to the original position (just like the suspension pushes the wheel back down). In the process your body feels the effect of stabilizing the weight. Now change the 25 lbs dumbbell for a 5 lbs dumbbell, and again someone pushes the 5 lbs dumbbell toward you. This time as you absorb the push your body hardly moves, and this is because the ratio of the dumbbell (unsprung weight) and your body (the vehicle) is much lower.
So just reducing the weight of your wheels+tires can improve ride quality. I haven't seen a definitive weight listing for the OEM 18" wheels, but my guess is they're ~32lbs (does anyone know how to look this up?).
I'm currently planning to buy some Avant Garde 310s:
M310 - Avant Garde Wheels
The 18x8s are 23 lbs, nice and light. I love the look, and word on the forums is that these are very strong (very crack/bend resistant).
I'm also considering the OZ ULTRALEGGERA (18.6 lbs, one of the lightest):
Oz Racing - OZ Racing - SPORT - ULTRALEGGERA
I'm going to stick with 18" since I find that a good overall size. 18" wheels + tires are almost always less weight than 19" wheels + tires having the same overall outer diameter. They also have lower rotational inertial, which allows for faster acceleration and deceleration. I'm not a big fan of the larger wheel diameters people are putting on their cars these days. I posted this in the S6 forum, but I'll repeat it here:
I feel bad for you guys with all these bent rims.
Makes me really question the current trend of buying larger diameter wheels.
I agree that large wheels often look cool, though I've seen some really large wheels that frankly look stupid, especially on trucks. But in general, large, wide wheels on sports cars do look bad ***.
But are they better?
Clearly large diameter wheels are more liable to get bent. I rarely hear someone with 17" wheels complaining about bent rims, sometimes with 18"s, but people with 19"s and 20"s it seems to happen much more frequently. Large diameter wheels mean less tire sidewall, which means if you hit a pothole there's simply less tire to protect the wheel.
Interestingly, larger diameter wheels often don't perform better, either. Here's an interesting article from Car and Driver comparing different wheel sizes:
Effects of Upsized Wheels and Tires Tested - Tech Dept. - Car and Driver
The test car was a VW Golf. It's interesting to note the skid pad results and braking seem to be most influence by the kind of rubber used in the tire, not necessarily just the width of the tire.
And acceleration, fuel economy, ride quality, and sound are all improved by moving to smaller diameter wheels. My understanding is that many guys that track their cars have found that 17" to 18" wheels is the way to go. So it's interesting to note that in a competitive environment where performance matters more than looks, people are choosing smaller wheels, not 20 inchers.
And that's all in the dry. Smaller diameter wheels with narrower tires are also more resistant to hydroplaning, and are better in snow.
There's a lot going for 17" - 18" wheels. Just something to consider.
Makes me really question the current trend of buying larger diameter wheels.
I agree that large wheels often look cool, though I've seen some really large wheels that frankly look stupid, especially on trucks. But in general, large, wide wheels on sports cars do look bad ***.
But are they better?
Clearly large diameter wheels are more liable to get bent. I rarely hear someone with 17" wheels complaining about bent rims, sometimes with 18"s, but people with 19"s and 20"s it seems to happen much more frequently. Large diameter wheels mean less tire sidewall, which means if you hit a pothole there's simply less tire to protect the wheel.
Interestingly, larger diameter wheels often don't perform better, either. Here's an interesting article from Car and Driver comparing different wheel sizes:
Effects of Upsized Wheels and Tires Tested - Tech Dept. - Car and Driver
The test car was a VW Golf. It's interesting to note the skid pad results and braking seem to be most influence by the kind of rubber used in the tire, not necessarily just the width of the tire.
And acceleration, fuel economy, ride quality, and sound are all improved by moving to smaller diameter wheels. My understanding is that many guys that track their cars have found that 17" to 18" wheels is the way to go. So it's interesting to note that in a competitive environment where performance matters more than looks, people are choosing smaller wheels, not 20 inchers.
And that's all in the dry. Smaller diameter wheels with narrower tires are also more resistant to hydroplaning, and are better in snow.
There's a lot going for 17" - 18" wheels. Just something to consider.
08-28-2015, 08:53 PM
#17
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I'm currently planning to buy some Avant Garde 310s:
M310 - Avant Garde Wheels
The 18x8s are 23 lbs, nice and light. I love the look, and word on the forums is that these are very strong (very crack/bend resistant).
M310 - Avant Garde Wheels
The 18x8s are 23 lbs, nice and light. I love the look, and word on the forums is that these are very strong (very crack/bend resistant).
I love them on my car. I do however have the 19". I find that size to be the perfect mix of performance and appearance on the A6. And the 19" still have enough tire protection to not have to worry about bent rims like you do with some larger sized rims
08-30-2015, 06:33 AM
#19
Some years ago, one of the car magazines ran a comparison of different wheel/tire combinations. They figured out that an 18" wheel was the optimum. Gave you handling that was, essentially, indiscernible from the larger wheels, a better ride, cheaper tires , better acceleration (less weight to turn = more hp at the tire) and greater protection from road hazards.
A different article was doing stage developments to a car, putting it on the dyno after each mod. After they put big brakes on the car, it lost about 5-10 hp -- as the kit had bigger disks and more hp was used just to turn the disks. So, big brake kits are a great way to make your car go slower....in more ways than one.
A different article was doing stage developments to a car, putting it on the dyno after each mod. After they put big brakes on the car, it lost about 5-10 hp -- as the kit had bigger disks and more hp was used just to turn the disks. So, big brake kits are a great way to make your car go slower....in more ways than one.
08-30-2015, 08:15 AM
#20
AudiWorld Super User
At night, it's almost impossible to avoid these despicable things on black asphalt. Same during the day after a hole-filling rain. And even if you do spot them, many of our two lane roads are narrow, making it difficult to drive around them if there's oncoming traffic. Wheel straightening in MA is a thriving business.