here is a bit of info taken from a well known motorsport "bible" by Paul Grimshaw:

"Light alloy wheels enhance vehicle performance by reducing unsprung weight and rotational mass while providing a medium through which disk brakes can radiate heat.

Reducing unsprung weight minimizes the load placed on controlling the motion of the wheels and tires. The result is better handling.

The use of light-weight alloys in wheels reduces rotational mass. This means that less energy will be required to accelerate the wheel. Given that each pound of rotational mass lost provides an equivalent performance gain as a 10 pound reduction in vehicle weight, the benefits of light alloy wheels on vehicle performance cannot be overlooked.

Most light alloy wheels are constructed of aluminum or magnesium. As a result, they act as better heat sinks for the brake disks to which they are attached.

To minimize the incidence of structural imperfections, quality wheel makers "spin cast" or machine their products from a solid billet. Chrome flashing (which requires the application of heat to the finished alloy) is avoided in cases where maximum strength is desired. Surface imperfections and rough edges are smoothed to further avoid stress cracking. Really fanatical wheel manufacturers then slowly apply heat to the wheel under laboratory conditions to "temper" the wheel for maximum strength. If the wheel is intended for motor sports use (ie. the wheel is a competition quality product) , a quality manufacturer will x-ray or dye test the product prior to sale.

Wheels made for light road use are usually cast. Lacquer is applied to cover cosmetic imperfections. The wheel is neither heat treated, nor inspected for internal imperfections. This results in a wheel suited for the average passenger car, but incapable of standing up to the rigors of motor sports use.

Wheels made primarily for "looks" are the poorest of them all. Their designs are marginal at best, as are the materials and manufacturing processes used. Hint: With some exception, many "chromed" alloy wheels can be lumped into this category."

I found some specs, and a typical 20" aftermarket chrome wheel like a Lowenhart can weigh as much as 20 pounds more than a stock AMG wheel (depending on style and size). 20x4= 80. In performance terms, it is a theoretical equivalent of adding 800 pounds to the car's sprung weight.

Pretty amazing.

 

Thanks for posting that. Really good info!

 

How good are the Kleemann TS-6s?

http://www.kleemann.dk/site/Main/accessories/wheels

KLEEMANN TS-6
Inspiration for the KLEEMANN TS-6 alloy came from the kompressor screw, and the design gives great consideration to weight and function. The centre rim is rotary forged, CNC machined and diamond polished, followed by several layers of clear coat. The two-piece outer rim section is polished alloy. The comprehensive manufacturing process reduces the rims' total weight up to 30 percent compared to a conventional alloy rim.

The unique shape of the TS-6 rim star augments the aerodynamics of the car as it exhausts the air from underneath while driving. In addition to reducing negative lift this also increases cooling of the brakes and improves the handling and stability of the vehicle

 

The TS-6 is a very good wheel from what I understand, although I am not sure it is forged. Forged wheels are lighter and stronger. Most wheels from Kleemann, Renntech, Brabus, etc. are pretty good wheels. HRE, definitely BBS, AMG, these guys make good strong, quality lightweight wheels.

The problems are with all these new wave of manufacturers that have come into market in the last few years that make the big wheels, that have very little quality control, and are very heavy. As stated the chrome plating forces a lower wheel strength during manufacturing and it does nothing for dissipating brake heat.

Also bigger is not always better, sometimes it is worse for overall performance. I honestly think for most high performance cars 18's are just right, 19's are good for some serious racing on very smooth roads, and 20 and anything over is just going to start affecting performance numbers negatively. If you do get aftermarket wheels, 2 and 3 piece wheels are always better than cast wheels not only in terms of weight and strength, but also you can replace the hub only if you bend it. You may be thanking yourself later for that one.

 

Some more interesting facts:

Center section of the Kleemann TS-6 is forged. In 19x8.5 and 19x9.5 the TS-6 is 26 and 27 pounds per wheel respectively. Cost is around $1600/wheel.

The AMG CL65 wheel is 33 and 34 pounds in those same sizes. The cast CL55 double spoke wheel is about the same weight although it is not of the same strength (and is not a multi-piece).

Older style AMG 5 spoke wheels in 18" sizes are just over 28 pounds each.

A BBS RS-GT is 19x8.5 is 21.4 pounds each. The lightest of all these mentioned. Its also one of the strongest. BBS is perhaps the best known manufacturer in Motorsport racing. This wheel can be had for around $700/each; less than half of the Kleemann TS-6.

Certain "California" style wheels like Lowenharts, Lexanis, Dubs, Elites, etc, weigh between 40 and 50 pounds each.

Chrome plating adds an average of 2-4 pounds to any wheel. Just the plating itself is that heavy.

There are now over 40 manufacturers of chrome alloy wheels, most have sprung up in the last five years.

Chrome alloy manufacturers do not make wheels for factory cars. The specs they have to meet are not the same as what vehicle manufacturers specify, in terms of weight, nor strength. Because of this, their low materials cost and high selling price, this category is now one of the most profitable categories of aftermarket parts.

Typicaly the lightest wheels tend to be thin 5 or 6 spoke designs.

I hope this info helps for when its time to change your baby's shoes.