Find lighter brake rotors, I am looking at the carbon fiber rotors, I can cut the weight in half on a rotor. Match this a lighter wheel and it might make a difference. Tim

Yes.

I took my heavy stock steel wheels off and put Weld Draglites on. The Welds were so light you could flip them around with one hand like they were cardboard.

And, to answer your question, in my case it did not make a lick of difference in day to day use.

Damn. Maybe some ov us are just more sensitive than others... I went from 15x7" (28lbs) cop rims to 15x7" Weld Drag Stars (13lbs). Tires might have been +/- 1-2lbs, not much, dont even remember which way. The difference was drastic. So much so i drove on those Welds... against the advice ov many friends... until i bent two ov them. That was just in daily driving (hard driving... but no curbs or bumps). LIGHT rims... but flimsy as hell. Gonna go with 19lb 8"'s on my Challenger instead ov the 26lb 8" steelies and caps, and yeah, i expect it to make a noticeable difference.

Another interesting anecdote... We swapped rollers on the girlfriend's 96GT from the stock 46lb 8" rims and 245's to cheapo (read solid, but HEAVY) E-bay 18x10's and 275/295's. They were 57/59lbs. The car slowed noticeably. Yes, the added width was worth a bit there i'm sure, but not all. The strangest thing was, that even now we had a nice open wheel... with LOTS ov airflow... we could not keep rotors on that car. In 4 years we went through 3 sets ov rotors... and the second set were 'the best' you can buy at the local shop. All that added grip really laid a taxin' on them poor little rotors. Did not expect that. My own 96GT (same stock rollers) never even got a brake job in the 3 years and 30K i owned it, and that was with much harder driving.

This makes zero sense.

Some of you need a critical thinking class..

Yes its good to bring examples and illustrations but we do not use deliver trucks as a template for making our cars perform better.

Aluminum wheels on trucks may be there because the customer wants them, they are lighter, they look better or their budget says so. Trying to sound positive and I hope you recieve it this way.

I will, but physics apply no matter what the end vehicle, plane, truck, car, lighter is better, etc, on this topic, no matter what the personal desires of the users or how they apply those desires.

IMO this topic might also benefit from some discussion on how to measure a driveshaft angle and maybe which engine oil is the best to use as well...

It makes perfect sense. So off you go.

Think I will try some sloot mags and see what happens.

Yes, inertia is your enemy and you are proving the point: Tires and wheels are exactly like extra flywheels at each corner of the car - They are mass the engine has to keep accelerating throughout the whole run. Less mass is a faster car.

- Art

I agree, as I stated earlier they are four flywheels. And not only does our vehicle have to accelerate them, it has to decelerate them too.
And they located at the four corners, much worse than the actual "flywheel" which is extremely idealy located!

Light wheels are a huge issue. The autocrossers know this!

A gyroscope would be a better analogy for wheels and tires. A gyroscope will resist ANY change in direction, that also includes acceleration in both the positive and negative direction.

Less weigh means less gyroscopic effect

https://woodgears.ca/physics/gyro.html

Uhh, still no.

Some of them can be quite heavy actually..

If you want to save weight, a forged aluminum wheel is going to be lighter than a cast one (especially an older slot mag that only has smallish windows with no material)

Just weigh them. Most ov those old-school slots were way light. I remember 18 and 19lb 15x8" rims. The old bias-ply 'performance' tires were lighter than radials too. Could make for a fairly aggressive weight loss where it counts. Almost worth using...

All those old CAST aluminum rims were (in general) light. Now... i wont say they were strong... but they were light. You know how the saying goes...

Modern forged is obviously badass. But damn... man, expensive.

Okay, here is some unscientific data using my bathroom scale.

On the front, I went from Cragar Soft 8, 15x7, with 235/60/15 Futura GLS to the Summit 531 alloy, in 15x7 with the same 235/60/15 tire.

Cragar Soft 8, 15x7, with 235/60/15 Futura GLS weighed about 51 lbs.

Summit alloy, 15x7, with 235/60/15 Futura GLS weighs about 43 lbs.

Some other measurements with the bathroom scale:

Chrysler 15x7 police with 235/60/15 Futura GLS weighs about 50 lbs.
Chrysler 15x7 police with 215/65/15 Cornell 1000 weighs about 45 lbs.
Chrysler factory 15x7 steel with 235/60/15 Goodyear Eagle ST weighs about 45 lbs.

Don't take any of that as gospel, because those measurements were made on an analog bathroom scale.

Butt dyno test will probably be overnight sometime. If it works out, I will switch the 15x8 steelies in the back with alloy wheels.

I'm not going to lie, but I kind of find this thread a little funny.

Yes, going to a lighter wheel should technically make your car faster. How much? It depends on what you have on there now vs what you plan on putting on. By decreasing weight, you're decreasing the amount of inertia required to rotate the wheel (i.e. less power to rotate). But in another sense you can also think of it as an aid to steering as now you have less mass to rotate side-to-side.

If you want to have a fun math exercise and a very rough ballpark as to how much less energy is required to spin your wheel, treat the wheel and tires as cylinders. For the wheel, the energy needed to rotate it is Iz = (m*r^2)/2. Where m is the mass of the wheel and r is the radius. For the tire, Iz = (m/2)*(R^2+r^2). m is the mass of the tire, R is the overall diameter of the tire, and r is the inner diameter of the tire (or just use the diameter of the wheel). Add the two together and you'll see the total energy. Do it for both setups and take [(IzOld/IzNew) - 1]*100% to find out how much more energy your old setup takes to spin than your new setup.

Wiki for equations: https://en.wikipedia.org/wiki/List_of_moments_of_inertia

If you look at the formula, you're going to notice that a change in radius of the wheel or tire is going to have a larger effect than changing the weight of the wheel. The radius is an exponential. Also, if you think about it, a tire weighs about about the same (+/- 15% depending on wheel and tire setup) of what the wheel weighs. So, technically going to a smaller or lighter tire will likely have more of an effect than a lighter wheel since all of the mass of a tire is outside the perimeter of the wheel (i.e. farther from the center of rotation). Most people have the problem; however, with traction going to a smaller tire. As mentioned before, the rears of a drag car are fat and meaty to get as much traction as possible (notice that a lot of people use lightweight wheels though), but on the fronts, they use pie cutters as they're easier to rotate about its axis.

Recent article testing / discussing effects of lighter wheels:

http://blog.caranddriver.com/tested-quan...n-fiber-wheels/

If nothing else, the lighter wheels make it a little easier for me take them off and on and move them around. I didn't care about that 25 years ago but I am starting to now.

Those tests of aluminum versus carbon fiber wheels are interesting, particularly the coast down.

In the Bosch Automotive handbook they give the equations for finding tire rolling resistance and aerodynamic Cd by coasting down from 60 mph.

Others have written that it is better to find these two values by coasting down two different grade hills at "terminal velocity"
because this is a steady speed test,
And rotating mass like wheels, driveshafts, gears, etc,
cannot add or subtract flywheel rotational energy
to skew the measurements.

The Car&Driver tests show that 20 lbs of wheel weight can indeed be measured by common stopwatch or ruler.