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[49ER ROLL]

older article but some good information...enjoy!

A quick synopsis is below:
Regular High Rigidity Enkei GTC-01 18×10 +22: 23.76 lbs.
Specially Lightened Version Enkei GTC-01 18×10 +22: 19.8 lbs.

The weight of the lightened version was reduced by 3.96 lbs. Both used Advan A048 (265/35-18 M-Compound). Testing was performed at Ebisu East Circuit using MCR’s Z33 driven by Kobayashi and under the same specs (ie., tire pressure, # of laps, etc.)

Regular High Rigidity GTC-01
Best Lap: 1 min. 4.646 seconds
Top Speed: 147.16 km/h @ 17.83 seconds

Specially Lightened GTC-01
Best Lap: 1 min. 5.045 seconds
Top Speed: 141.46 km/h @ 17.74 seconds


A very rough and quick recap: The surface temperature of the tires for the less rigid, specially lightened GTC-01 were higher overall with extensive wear on the outer portion while not enough contact/usage on the inner portion. The high rigidity regular version GTC-01 showed even usage throughout the inner and outer parts of the tire. Also, the low rigidity, lightweight version wheels gave/bent when taking aggressive high speed turns even affecting the height of the car which even led to scraping and alignment problems. Furthermore, the lighter version accelerated much quicker, but ultimately did not lead to faster times. In summary, Kobayashi expressed that a balanced wheel with both rigidity and lightweight characteristics is important, but he never imagined that the effects of rigidity played such a large role.

[smmmurf]

wow that is very interesting stuff, that is a dramatic difference (.4 second)

[swamp2]

Very interesting read. Thanks for posting.

[Eddy@ApexRaceParts]

They took a wheel that was JWL/VIA certified for a certain load rating (industry standard), they then shaved 3.96lbs of material off it. Although they say the wheel is "still capable of enduring the driving field without fracturing", the wheel is clearly a weak, and would fail a strength test at the minimum required strength rating.

I absolutely agree that design has a lot more to do with rigidity then material (forged vs. cast...), but it's actually an apples to oranges comparison because one wheel is extra weak.

You are not going to get 3.96lbs of material off a wheel by removing material from the front and back of a hub. The material between the lugs on the backside is weight you can reduce without weaking the wheel. BBS does a really nice job of this on their die forged wheels. To reduce weight that much you have to take material off the spokes or even the barrel. And if you do that, you've made a really weak wheel.

When doing some initial testing years ago, I found that a slight change in spoke design that only effected a 0.2lb reduction in overall weight, in some cases resulted in spokes cracking during crush testing. At a lower load rating the spokes wouldn't crack. We went through 3 rounds of crush testing on a prototype after that just to study these minor changes. Those changes also effect rigidity.

Just as an example, adding 2mm~ of material to the backside of the spokes on our 17" wheels added about 0.8lbs~ of weight. Consider how much needs to be removed to save 3+ lbs if you can only find a fraction of a pound in savings around the hub area.

The point is, if you make a wheel weak, it will suck. Does that mean light weight wheels are nearly as weak as the one tested in the article above? No, because almost no manufacturers produce wheels that sacrifice that much strength. The only way a wheel could be that weak, would be to not meet strength requirements. Sadly there are wheel manufacturers out there that willing sacrificed strength in exchange for reduced weights. They produce/ed wheels below required load ratings, even though they claim compliance and certification.

[Victory Road]

I remember reading about this a while back. Good article and very informative.I'm to glad to see it has made its way to M3Post.

Kobiyashi-san is very deep into the circuit racing world in Japan, and his R34 GTR has always been a personal favorite.
Also, M.C.R. stands for Matchless Crowd Racing, how

[Mahmood07]

I hope my advan RS perform better than OEM 19's

[sensi09]

Oh found an old post I made about this article.

Originally Posted by Sensi09

This is good information, but we can't measure for rigidity, so the information can't really be put to use. Heavy wheels won't necessarily be more rigid and light wheels don't necessarily have to lack rigidity.

For the lightweight wheel, they take a regular wheel and basically chip away at it to make it lighter. If you take any properly designed wheel and take parts off it, I doubt it will react and perform in the same manner. Lightweight, forged wheels are designed as such, so I doubt they will be lacking in rigidity.

If this were a U.S. article someone would say it was biased, and I'm not sure we can count that out. Enkei has quality wheels, but they claim that a wheel with the same design will weigh the same whether it's cast or forged. Also, the wheel will have the same strength/rigidity whether its cast or forged. There are some advanced casting techniques out there, but I don't know about that. Enkei goes on to say that most of their wheels are cast....