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[TazioNYC]

Looking at both the BMW Performance and the new Breyton GTS-R wheels...I like the looks of the BMWs somewhat better, but am intrigued by the effects of reducing unsprung weight. I think it would be 35-40 pound of wheel weight reduction with the Breytons -- what could I expect to feel with that reduction? How would the handling/steering change?

[Steve135i]

Usually with a lighter wheel will make the car hit bumps with less harshness. Also getting a lighter tire helps. I put a set of lightweight wheels/tires on my Accord and it rides smoother and seams to be a little quicker. But sometimes traction seams to be less? Maybe less weight touching the tarmack.

[bryan@mwerks]

We just put the Breytons on our long-term/project 135i. Combined with the Yokohama S.drive tires, they shaved a total of 35 pounds. The change in ride quality is mostly due to the non-runflat tire. But as far as acceleration goes, the car feels noticeably more powerful. In fact, the reduced mass has made it more difficult to launch well.

Full story is at MotiveMag

[gatorfast]

Hmm. I dont have a 135i, but I did change out my heavy stock wheels to light weight OZ wheels. Honestly, I didnt really notice anything in terms of a difference in acceleration. Maybe its more pronounced on the 135.

[mistermojorizin]

Originally Posted by Steve135i

Usually with a lighter wheel will make the car hit bumps with less harshness. Also getting a lighter tire helps. I put a set of lightweight wheels/tires on my Accord and it rides smoother and seams to be a little quicker. But sometimes traction seams to be less? Maybe less weight touching the tarmack.

weight touching the tarmack is probably like 5lbs or 10lbs less per wheel, which isn't significant for the car's weight (the tarmac doesn't know if its sprung or unsprung). the loss of traction is probably because the wheels are accelerating faster now, due to the lower intertial momentum. so more acceleration with the same amount of traction as before results in more wheelspin. kinda like people add piggybacks, they notice the traction control is going off a lot more.

or it could be a less sticky compound on the new tires.

[TazioNYC]

Originally Posted by bryan@mwerks

We just put the Breytons on our long-term/project 135i. Combined with the Yokohama S.drive tires, they shaved a total of 35 pounds. The change in ride quality is mostly due to the non-runflat tire. But as far as acceleration goes, the car feels noticeably more powerful. In fact, the reduced mass has made it more difficult to launch well.

Full story is at MotiveMag

Thanks so much! Any more pics of the car from 3/4 view or another angle?

[bryan@mwerks]

Here is a raw studio shot from the front. Hope that helps.

[TunedM2C]

^ Nice shot.

[bmwzimmer]

What size tires? Similar to stock? On the tirerack, they recommend 215's for both front and rear which is retarded...

[adc]

Originally Posted by bryan@mwerks

Here is a raw studio shot from the front. Hope that helps.

Could you please post the wheel/tire specs? Car looks gorgeous, and I like the wheels a lot (I'm probably not going to like the price though).

[Gary@TireRack]

Originally Posted by adc

Could you please post the wheel/tire specs? Car looks gorgeous, and I like the wheels a lot (I'm probably not going to like the price though).

There's an entire thread on that wheel. It's the Breyton GTS-R

[adc]

Originally Posted by Gill@Tirerack.com

There's an entire thread on that wheel. It's the Breyton GTS-R

Thank you, Gill!

[mikeo]

An old 'rule-of-thumb' is that 1 pound of unsprung weight equals 4 pounds of sprung weight. And yes you can accelerate and deccelerate a lighter wheel/tire faster, fuel mileage is just slightly better, and overall ride quality is improved. Reducing unsprung weight is a very big deal in racing and there are also proven benefits for street cars.

[DTNJNQ]

Someone mentioned above that less unsprung weight can cause less traction meaning the traction control operates more often.
Does this result in less performance and inferior handling?

[TazioNYC]

Originally Posted by mikeo

An old 'rule-of-thumb' is that 1 pound of unsprung weight equals 4 pounds of sprung weight. And yes you can accelerate and deccelerate a lighter wheel/tire faster, fuel mileage is just slightly better, and overall ride quality is improved. Reducing unsprung weight is a very big deal in racing and there are also proven benefits for street cars.

Great info, thanks!

[mikeo]

Originally Posted by DTNJNQ

Someone mentioned above that less unsprung weight can cause less traction meaning the traction control operates more often.
Does this result in less performance and inferior handling?

No. Less unsprung weight allows the suspension to better keep the tire in touch with the road surface, which results in better handling. Lighter rotational mass in the wheel/tire allow power, both engine and brake, to be slightly more quickly transferred to the road surface and is easily adapted to by the driver (better initial throttle and brake modulation), resulting in better performace overall.

[larryn]

+ 1 ^^What mikeo said, plus one caveat. With less rotational mass, it will be easier to "light 'em up" since there's weight to get spinning. The benefits that mikeo points out far, far out weight that potential detractor (which I do not see as a big detractor) though. You will simply need to initially apply the throttle a slight bit more judiciously, then tear ass on the track.

[DTNJNQ]

Originally Posted by larryn

+ 1 ^^What mikeo said, plus one caveat. With less rotational mass, it will be easier to "light 'em up" since there's weight to get spinning. The benefits that mikeo points out far, far out weight that potential detractor (which I do not see as a big detractor) though. You will simply need to initially apply the throttle a slight bit more judiciously, then tear ass on the track.

Does this mean that something like the Sprint booster is no good with light weight wheels as it would be too easy to "light 'em up"

[larryn]

I really have absolutely no experience with the Spring Booster, so I cannot comment. Sorry. :iono: