[dradernh]

Originally Posted by SoftShoe

asking for some real world numbers that would make the case.

https://grassrootsmotorsports.com/ar...really-better/

[SoftShoe]

Thank you.

It seems the relevant passage for my interests may be:
“We’ve compared light and heavy wheels a few times before, and the results consistently showed a negligible difference”

But the fact that they pulled 12 pounds per corner out of a lemons Miata and got 0.16-0.46 seconds faster on a one minute track makes me wonder…

What would the equivalent per corner weight loss need to be to impact the significantly greater power and weight of our cars enough to show similar gains?

[freakystyly]

Of course there's better ways to make up lap times than wheel weight. Weights are absolutely is noticeable but very hard to prove the benefit in a daily driver on the street.

I had Arc-8s for summer and a heavy winter setup on a previous car. The swap was night and day but you quickly become accustomed to the new setup.

Style 162s weighed approx 30lbs each just the wheel vs 18.5lbs for the Arc-8 so there was a huge margin there. Winter wheels have more tread and should be a no brainer that they weigh more.

[USA-RET]

I can't find it now, but there was a website that compared a Camaro with stock wheels, heavier wheels and lighter wheels. They did dyno tests with each wheel and it showed a WHP and WTQ loss when adding heavier wheels (compared to the stock wheels) and a gain of WHP and WTQ when adding lighter wheels (compared to the stocks wheels). The lighter wheels and tires shaved a total of 38 lbs from the stock wheels and tires and netted a +10 to WHP and +11 WTQ on the dyno (I may have the numbers reversed, but either way, there is a big gain IMO). I was able to shave exactly 38 lbs off my Mini Cooper S with new Tires and wheels and immediately noticed a diff in handling (more lively). Naturally, if you drive the car in traffic to and from work, these gains will not be noticeable. If you autoX or race, you should see a diff in lap time or 1/4 mile or 0-60 times.

I always found it interesting that guys will spend $500 on a CF intake to gain 9 HP and then throw a set of Foose boat anchors on their car and lose all that 9HP and then some.

One only has to look at the F1 teams and the thousand$ they spend on engineering lighter wheels.

[dradernh]

Originally Posted by SoftShoe

Thank you.

It seems the relevant passage for my interests may be:
“We’ve compared light and heavy wheels a few times before, and the results consistently showed a negligible difference”

But the fact that they pulled 12 pounds per corner out of a lemons Miata and got 0.16-0.46 seconds faster on a one minute track makes me wonder…

What would the equivalent per corner weight loss need to be to impact the significantly greater power and weight of our cars enough to show similar gains?

In which performance driving activities are you or will you be using your car?

[SoftShoe]

None.

Just “canyon carving.”

I like to explore the car’s behavior on very tight, winding roads where I can engage it’s dynamics without breaking the law. Most of these roads have some sections that aren’t particularly smooth and include longer less winding sections that accommodate higher speeds.

Because of that, I’ve considered going square with 245s on 17s. If I’m not mistaken, you have some experience with that. I’d welcome your thoughts there and any other advice you find relevant (including “stock should be fine”).

[dradernh]

Originally Posted by SoftShoe

None.

Just “canyon carving.”

I like to explore the car’s behavior on very tight, winding roads where I can engage it’s dynamics without breaking the law. Most of these roads have some sections that aren’t particularly smooth and include longer less winding sections that accommodate higher speeds.

Because of that, I’ve considered going square with 245s on 17s. If I’m not mistaken, you have some experience with that. I’d welcome your thoughts there and any other advice you find relevant (including “stock should be fine”).

Given your use case, I do think that stock should be fine.

I'm assuming you'll continue using Max Performance Summer tires. If that's the case, I'd recommend staying with the Michelin PSS that came on your car as they have greater tread widths than do, say, the newer Michelin PS4S. That's in the stock staggered sizes. That data can be seen by clicking on the Specs tabs on these Tire Rack pages:

Michelin Staggered PSS: https://www.tirerack.com/tires/tires...ggered%20Tires Tread Widths: F – 7.9"; R – 9.2"

Michelin Staggered PS4S: https://www.tirerack.com/tires/tires...ggered%20Tires Tread Widths: F – 7.7"; R – 8.4"



Moving on from stock, my opinion is that a limited slip differential would offer you the greatest bang-for-the-buck in terms of a useful and perceptible increase in enjoyment during your canyon runs. However, an installed LSD costs quite a bit more than $1K.

The only 17" wheels I've run had narrow winter tires on them. Lighter, square 17s with 245s on them would certainly make the front end more responsive to your steering inputs and to significant road bumps that you might encounter on your drives.

If you were to choose to do that, I'd suggest adding negative camber at the same time. That would allow you to get the full use of the tread widths in the turns. Running at legal speeds, however, I don't see you getting full value for what the upgrade in wheels, tires, and suspension would cost.

I'd focus on the LSD (however long that might take) and see if that satisfied your need for a more responsive car in the twisties. If you do get around to doing that, I also suggest installing a set of Turner Motorsport solid aluminum rear subframe bushings so that you get more of what the LSD has to offer. You can see and read about the bushings here: https://www.turnermotorsport.com/p-3...ame-mount-kit/. My experience has been that any added NVH has been too slight for me to notice. Together, the LSD and solid bushings create a very different car when pressing on the throttle coming out of corners. This makes a difference when the pavement is wet, too, which can be a safety concern as much as a performance concern.

[SoftShoe]

From me: Thank you for your generous investment in advancing my interests.

Speaking for everyone else you’ve helped: We’re grateful for the information you put into these responses all across the forums. We know that the knowledge and time it takes doesn’t just appear out of nowhere.

**Also, I already did the LSD �� - considered it a must have. Didn’t do the solid bushings at the time (and sometimes I do sense a bit of squish).

[MarkDemma]

More //M badges

[JMcLellan]

One thing to mention is that if this $1000 was spent on my M240 right now my kiddos would be having 2 Christmases starting this December. So maybe spend $1000 and save $5000 on a good divorce lawyer?? The wife doesn't get why any of this car parts stuff should be purchased and to a certain extent she isn't wrong but it's just what you do for the cause.

[60_Driver]

Originally Posted by SoftShoe

From me: Thank you for your generous investment in advancing my interests.

Speaking for everyone else you’ve helped: We’re grateful for the information you put into these responses all across the forums. We know that the knowledge and time it takes doesn’t just appear out of nowhere.

**Also, I already did the LSD �� - considered it a must have. Didn’t do the solid bushings at the time (and sometimes I do sense a bit of squish).

I like this thread. I also completely concur with what Softshoe said regarding Doug’s insight. Always incredibly helpful & kind. Thanks again!

[daneagles]

Originally Posted by SoftShoe

Is that true?
Does saving 15 pounds of rotating mass really do anything when I’m pushing around 3600 pounds?

Not saying it doesn’t.
Just stating the reason for my incredulity.
Also asking for some real world numbers that would make the case.
And, if those stats exist, some wheel recommendations to turn them into reality for me.

I got a set of Apex wheels with PS4S in the stock size and when I drove the car for the first time, I could have sworn I had upgraded to a more aggressive brake pad and flashed the car for an extra 20-30 HP. The difference in acceleration, braking and handling from true lightweight wheels on our cars is absolutely noticeable and makes a huge difference.

[dmaxdmax]

I'd do what I've just done for my m235i...buy plugs, air filters, fluids (trans and diff), belt, pulleys...and if I had any left over, I'd buy some stock so I had money for when it needed more work soon.