[M2Sky]

Originally Posted by m2not1LE

The thing is that BMW designed the rest of the suspension around the 19" front wheels (and the resulting sidewall height) and vice versa.

As always, maintaining absolute correct factory wheel offset is essential in any non-stock wheel choice because incorrect offset messes up the kinematics of the suspension itself. BMW M engineers go to great length in ensuring that each suspension components (and wheels/tire) componenets work synergistically with the others. I think way too many folks overlook that.

I also think many overlook the adverse effects of a "plus" wheel/tire configuration, as detailed in this article:

https://www.caranddriver.com/feature...-wheels-tires/

Best wheel upgrade for these cars is choosing a forged alloy wheel (6061-T6 aluminum is the most common) and keeping all other variables exactly the same as factory spec - offset in particular. This provides for lighter wheels, which in turn reduce unsprung weight, wheel/tire rotational inertia and overall vehicle weight.

You are correct regarding kinematics I won’t dispute that but this is taken to an extreme.

Your implying bmw set this car up to be the best it can be which they didn’t. They set it up to conform to what they want from it. Compromise of comfort to handling along with a cost budget and meeting dumbass EU regulations.

Any modification from stock would be a compromise in one direction for another or could just be crap in every direction except athletics lol.

I could have taken it the wrong way but the impression I get from your posts is your car will shit if you change your wheels to non oem fitment which simply isn’t true.

[Ronin76]

Originally Posted by M2Sky

You are correct regarding kinematics I won’t dispute that but this is taken to an extreme.

Your implying bmw set this car up to be the best it can be which they didn’t. They set it up to conform to what they want from it. Compromise of comfort to handling along with a cost budget and meeting dumbass EU regulations.

Any modification from stock would be a compromise in one direction for another or could just be crap in every direction except athletics lol.

I could have taken it the wrong way but the impression I get from your posts is your car will shit if you change your wheels to non oem fitment which simply isn’t true.

That is exactly what his posts imply.

[Geighty7]

I rub at full lock steering.

285/30/20 front
305/30/20 rear

Dialed down 1.4’ drop front and back.

I’ll likely shave some liner or buy the clearance aftermarket’s.

As for ride feedback- I just got them done yesterday so I do not have a ton. I also got much needed alignment…so overall my ride is excellent. I haven’t taken any fast turns or canyons yet (I likely won’t with these wheels) but I assume in all honesty 20 in front might decrease performance, but increase looks.

Reason I’m saying that is you have more meat on the tire of course from factory or going with a smaller wheel up front. It’s pretty standard way of thinking.

Will you notice? Depends if you track it. My car is a faux track speck- meaning it looks like it’s track ready, but it’s showroom track ready if you catch my drift.

If I was building a true track mule or canyon carver, I’d opted for 19 or 18 squared with 295 or 305’s.

For cars & coffee standouts, overall looks, and head turning…20 all around is the way to go.

[m2not1LE]

Originally Posted by M2Sky

You are correct regarding kinematics I won’t dispute that but this is taken to an extreme.

Your implying bmw set this car up to be the best it can be which they didn’t. They set it up to conform to what they want from it. Compromise of comfort to handling along with a cost budget and meeting dumbass EU regulations.

Any modification from stock would be a compromise in one direction for another or could just be crap in every direction except athletics lol.

I could have taken it the wrong way but the impression I get from your posts is your car will shit if you change your wheels to non oem fitment which simply isn’t true.

I've implied none of that. Rather, that is merely your emotional interpretation of what I stated.

I merely provided engineering commentary (I am a mechanical design engineer) backed by a third party source addressing the pitfalls of choosing wheels with offsets that differs from factory spec and/or employing spacers.

That it is. I'll also note that I've made suspension/wheel/tire altercations to many of my own vehicles. Thing is, I actually know what I'm doing in making those choices, rather than merely going for "the bling factor."

Now please post a supporting link detailing the specific "dumbass EU regulations" that impact wheel offsets and suspension kinematics.

[Ronin76]

[M2Sky]

Originally Posted by m2not1LE

I've implied none of that. Rather, that is merely your emotional interpretation of what I stated.

I merely provided engineering commentary (I am a mechanical design engineer) backed by a third party source addressing the pitfalls of choosing wheels with offsets that differs from factory spec and/or employing spacers.

That it is. I'll also note that I've made suspension/wheel/tire altercations to many of my own vehicles. Thing is, I actually know what I'm doing in making those choices, rather than merely going for "the bling factor."

Now please post a supporting link detailing the specific "dumbass EU regulations" that impact wheel offsets and suspension kinematics.

Please don’t ever get into teaching. 🤣

Your far more educated than I on this however due to my miss understanding of what you meant I was using it as an example of how cars are not necessarily the best they could be in one way or another due to having to conform to various requirements.

I’m interested to know as an engineer do you look at everything on your own cars from a performance / efficiency perspective or is there a subjective feel basis in there too?

[maxwell smart]

Whoever thinks the M2 is setup perfectly from the factory would be mistaken.
If your intentions are to just cruise it, the package is close to perfect.
But if you take the car to the extreme you find it understeers like crazy, squealing the front tires all over in the places you want to hold speed, but you cant hold your speed.
I lowered the front of my car using the parts bin method, using oem BMW m3 competition front springs.
The car is still all oem but, I reduced the amount of understeer getting very close to neutral with this change by lowering and stiffening the front .
One thing should be understood, BMW M2 vehicles are fully adjustable race cars if you understand how to make the changes.
oh, and I just installed 824m wheels as well, other direction from this post but super sick.

[Ronin76]

Originally Posted by maxwell smart

Whoever thinks the M2 is setup perfectly from the factory would be mistaken.
If your intentions are to just cruise it, the package is close to perfect.
But if you take the car to the extreme you find it understeers like crazy, squealing the front tires all over in the places you want to hold speed, but you cant hold your speed.
I lowered the front of my car using the parts bin method , using oem bmw m3 competition front springs.
The car is still all oem but, I reduced the amount of oversteer getting very close to neutral with this change by lowering and stiffening the front .
One thing should be understood, BMW M2 vehicles are fully adjustable race cars if you understand how to make the changes.
oh, and I just installed 824m wheels as well, other direction from this post but super sick.

Oh man…now you did. Sheldon is going to tell you all about him being a mechanical engineer, all the things he has published, and a bunch of articles to read.

[maxwell smart]

Lol , I noticed skimming thru this thread there's some big math being thrown around , making it sound as tuning a motorsports chassis is something only a BMW M engineer can accomplish.
I've found thru owning an assortment of vehicles, the best ones are the cars that are the most adjustable so a motorsports engineer can tune it to their respective application.

[MineralGreyMetallic]

Originally Posted by maxwell smart

Whoever thinks the M2 is setup perfectly from the factory would be mistaken.
If your intentions are to just cruise it, the package is close to perfect.
But if you take the car to the extreme you find it understeers like crazy, squealing the front tires all over in the places you want to hold speed, but you cant hold your speed.
I lowered the front of my car using the parts bin method, using oem BMW m3 competition front springs.
The car is still all oem but, I reduced the amount of understeer getting very close to neutral with this change by lowering and stiffening the front .
One thing should be understood, BMW M2 vehicles are fully adjustable race cars if you understand how to make the changes.
oh, and I just installed 824m wheels as well, other direction from this post but super sick.

That is one thing I'm really noticing as a difference between F87 and G87.

G87 understeers way more than I'd like. Never experienced that with my F87.

What will help that?

[maxwell smart]

Hello MGM,
I believe the US cars are engineered specifically to not be as good as the m3 and m4. How did they do that you ask, they jammed us with tall and soft front springs . If the vehicle is tuned to be correct with lower stiffer front springs it takes on a new personality .
If you look at information to reduce understeer, lowering helps, and stiffening helps. there are other ways to reduce understeer as well, you have to research and find out what you can apply to your setup.

[aerobod]

Originally Posted by maxwell smart

Hello MGM,
I believe the US cars are engineered specifically to not be as good as the m3 and m4. How did they do that you ask, they jammed us with tall and soft front springs . If the vehicle is tuned to be correct with lower stiffer front springs it takes on a new personality .
If you look at information to reduce understeer, lowering helps, and stiffening helps. there are other ways to reduce understeer as well, you have to research and find out what you can apply to your setup.

G87 has stiffer front springs than the G80/2 and the same slightly softer rear springs of the G81 to give it a bit more power-on oversteer. No "engineered specifically to not be as good as the M3 and M4".

[MineralGreyMetallic]

Will the 20" wheel with smaller/firmer tire sidewall help alleviate or exacerbate understeer, or too hard to know?

[maxwell smart]

Aerobod, I took my car apart in an effort to tune out the high front end height. It just didn't seem right to me. Of course I did some measuring. The original front spring on my car used wire that measured 13.5mm and is wound to be at a tall height. The m3 front spring I used in its place measured 14.1 mm wire and was visibly shorter in its wind, I think it was like 8mm shorter in height on the bench than my original. The original rear springs use 14.3mm wire , and were the exact same wire size as the m3 kit I bought . So I have m3 front and m2 rear springs right now and I think the calibration seems great. Not trying to argue, just mentioning I'm having success with just a front spring change. From the factory the front spring is soft I think compared to g80/82 that use a thicker wire.
The intro video from a year ago when the M engineers talk about the calibration of the suspension , is said exactly as you mentioned. stiff front softer rear, I remember the video. but if you go to the parts bin and do some measuring you discover there's way better choices for the front than what we received. Everyone who changes to aftermarket is trying accomplish the same lower stance, I'm using oem parts to get the results I desire.

[Montaver]

The BMW wheel offsets are determined by EU requirements for snow chains. Given the choice they would develop a more aggressive offset to widen the cars track. All the manufacturers do this, look at Audi for example. If your spending money on aftermarket wheels there is no real downside to getting a more aggressive offset. A lighter wheel will be great for unsprung mass and has a ton of benefits (ride, suspension response etc).

[m2not1LE]

Originally Posted by M2Sky

Please don’t ever get into teaching. 🤣

Your far more educated than I on this however due to my miss understanding of what you meant I was using it as an example of how cars are not necessarily the best they could be in one way or another due to having to conform to various requirements.

I’m interested to know as an engineer do you look at everything on your own cars from a performance / efficiency perspective or is there a subjective feel basis in there too?

But I have taught, with many students strongly benefitting as a result, son.

I strongly urge you to better familiarize yourself with the rules of proper grammar.

Every other thing you stated or asked is equally off base.

We as a nation are doomed when the vast majority of others are either unwilling or unable to learn from those who know better through both formal education and decades of related real world experience.