The article does a very poor job of apples/apples and any sort of effective scientific method.
1) To be truly thorough, a test (ON THE SAME CAR) should be done with the R wheels (AND THE SAME SET OF TIRES). This will isolate the effect of the wheels rather than the blurred issue of the wheels AND tires.
2) As I pointed out in another thread, the tires which are at the outer dimension of the rotational assembly, count for WAY MORE rotational inertia savings than the wheels. A lb saved off the wheel is several times less impactful than a lb saved off the tire.
You can get most of the performance improvement by swapping to the equivalent (of the R) dimension Sport Cup tires.
Also bear in mind that the additional dimension of the super sports hurts both in terms of the weight AND the radius.
In essence, wanna see a neat trick? Take two identical cars, put a set of 30" tire/wheels on one and put a set of 29" tire wheels on the other and see which one is quicker in 0-60.
Weight savings are nice anywhere, and particularly so for unsprung weight, but the comparison assumes all the benefits are from the wheels and the reality is probably more the opposite, MOST of the improvements (both in acceleration and grip) are from the tires. The rest of the impacts in terms of tuning the suspension and such are definitely the wheels, but in terms of flat out acceleration, it's most likely the tires that comprise the majority of the benefit.
I'm going a step further and saying that the majority of the advantage of the wheel/tire package is in the tires.
The wheels save weight, which is a good thing and they have a reduced rolling inertia, but the majority of the reduced rolling inertia is due to the reduced weight of the tire. Reducing weight out at the end of the radius is exponentially beneficial compared to weight near the center.
Furthermore, the reduced tire size of the cup tires also creates an artificial gear ratio advantage, again, which helps to explain acceleration advantage in the R.
If I took two regular 350s and put one with 1" smaller tires, but everything else identical, you'd expect the smaller tire car to accelerate slightly faster, no shock there, the smaller tires help gearing and also reduce rotational inertia (and they're slightly less unsprung weight).
Now, the wheels obviously help in a number of indirect and obscure ways like overall weight, unsprung weight, dampening with respect to suspension dynamics as pointed out in the article, etc, etc.
The R also has stiffer front springs, a slightly beefier rear sway bar and a couple of other weight saving reductions. But in terms of the grip and rolling inertia at the wheels, the tires account for MOST of that.
And I disagree with the article's assessment of the alloy vs. carbon fiber for durability or abrasion.
Any idiot who things if you curb the R wheels and you will just be able to solve the problem with some paint is delusional.
I've installed plenty of carbon fiber in structural applications and I can tell you that it AIN'T designed for impact or abrasion performance. It's essentially carbon linear fibers with a resin binder and without both in place, the composite fails miserably. Scrape off the resin or damage the fibers or orientation of the fibers and it's not good. In that sense, alloy is going to hold up better (long term). That, and you could replace the standard GT350 wheels twice over before replacing the R wheels and still come out ahead (on $).
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