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      01-17-2021, 08:25 AM   #89
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      01-17-2021, 12:52 PM   #90
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Quote:
Originally Posted by solstice View Post
Quote:
Originally Posted by themnmd View Post
May be closer to M340 AWD setup ?
I totally forgot that the 340 got the M differential. In that case the 440 probably has it as well and it could be that only software differentiates the G8X?
I love my m340 X . the new M3's
will better handling and faster with an upgraded interior. Boss!! I will be waiting for the AWD.
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      01-17-2021, 01:05 PM   #91
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Quote:
Originally Posted by CanAutM3 View Post
To be fair, the video is a bit misleading, showing the tyres in front of another filmed with a fish eye lens. It looks like the G8X tyre is almost 50% wider . If they would have put the F8X tyre in front, it would have been much less impressive. Also, with the 255, they also chose the smallest of the F8X tyre .
Indeed. ZCP has 265 at the front, and my car has 275. No big deal.
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      01-17-2021, 01:14 PM   #92
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Quote:
Originally Posted by sasa.baska View Post
I wonder how will G80 drive in rain with 275 at front... with my F80 and 255 tire I have to reduce the speed a lot otherwise it aquaplans like crazy... def not confidence inspiring in rain
My second F80 M3 had 265 at the front and i didn’t experience more aqua planing compared to my 2015 with 255 fronts.

Then when I switched to Michelin Pilot Sport 4S (an “upgrade” by all accounts compared to the OEM Pilot Super Sport) and i went with 275 fronts, I’m still ok.

So I doubt it will be a major factor. After all, they do have occasional rain in Germany.
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      01-17-2021, 01:18 PM   #93
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Originally Posted by adc View Post
My second F80 M3 had 265 at the front and i didn’t experience more aqua planing compared to my 2015 with 255 fronts.

Then when I switched to Michelin Pilot Sport 4S (an “upgrade” by all accounts compared to the OEM Pilot Super Sport) and i went with 275 fronts, I’m still ok.

So I doubt it will be a major factor. After all, they do have occasional rain in Germany.
To be fair, the amount of standing water in highways in the US is completely different than in western Europe.

Anywhere in Spain for example they use draining asphalt on highways that allows the surface to be wet but you don't find puddles.

I didn't really understand aquaplanning until I moved here
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      01-17-2021, 01:41 PM   #94
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Originally Posted by SYT_Shadow View Post
To be fair, the amount of standing water in highways in the US is completely different than in western Europe.

Anywhere in Spain for example they use draining asphalt on highways that allows the surface to be wet but you don't find puddles.

I didn't really understand aquaplanning until I moved here
All I’m saying is my car feels no worse than stock with P4S 275 fronts compared to 265 PSS, in the US.

I’ve driven 3,000 on my car in Europe during Euro Delivery and know their roads have much better drainage, but even here in the US i don’t regret going wider at the front...
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      01-17-2021, 01:56 PM   #95
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Quote:
Originally Posted by adc View Post
My second F80 M3 had 265 at the front and i didn’t experience more aqua planing compared to my 2015 with 255 fronts.

Then when I switched to Michelin Pilot Sport 4S (an “upgrade” by all accounts compared to the OEM Pilot Super Sport) and i went with 275 fronts, I’m still ok.

So I doubt it will be a major factor. After all, they do have occasional rain in Germany.
As a tidbit, I have 265 PSC2 on my car's front axle, and honestly, driving in the rain has not been a challenge at all, so I decided to put PSC2 back on when they needed replacing.
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      01-17-2021, 02:26 PM   #96
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Quote:
Originally Posted by adc View Post
All I’m saying is my car feels no worse than stock with P4S 275 fronts compared to 265 PSS, in the US.

I’ve driven 3,000 on my car in Europe during Euro Delivery and know their roads have much better drainage, but even here in the US i don’t regret going wider at the front...
The advancement of wet weather tire performance in the last two decades has been truly immense. Back in the 80s and 90s I had cars with 185s and 195s that aqua planed pretty much every time it rained. Today I very seldom experience aqua planing with 255s...

I have zero concerns about daily drive ability and safety with the standard 275 or optional 285 fronts when shod with modern Michelins.

As far as comments of the new car not being much upgraded according to these videos. They say it’s partly faster than the M4 GTS so the implementations described here including tire/wheel selections sure seem to be working...

Last edited by solstice; 01-17-2021 at 02:32 PM..
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      01-17-2021, 04:23 PM   #97
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Originally Posted by mfurse View Post

- ...but it's ride and handling limits are too high to enjoy on the road."
So you believe that a car is only enjoyable in real life when its handling limits aren't that good? Maybe test a Porsche Turbo S then?
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      01-17-2021, 04:39 PM   #98
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Quote:
Originally Posted by solstice View Post
The advancement of wet weather tire performance in the last two decades has been truly immense. Back in the 80s and 90s I had cars with 185s and 195s that aqua planed pretty much every time it rained. Today I very seldom experience aqua planing with 255s...

I have zero concerns about daily drive ability and safety with the standard 275 or optional 285 fronts when shod with modern Michelins.

As far as comments of the new car not being much upgraded according to these videos. They say it’s partly faster than the M4 GTS so the implementations described here including tire/wheel selections sure seem to be working...
I certainly can predict a metric where the AWD G8X will be faster than the F8X GTS: 0-60mph
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      01-17-2021, 04:51 PM   #99
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Quote:
Originally Posted by CanAutM3 View Post
I certainly can predict a metric where the AWD G8X will be faster than the F8X GTS: 0-60mph
Lol, My first thought as well but I’m not sure he would have said “with optional Cup tires” if that is what he eludes to. That should not be needed for that
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      01-17-2021, 04:52 PM   #100
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Quote:
Originally Posted by mkoesel View Post
I didn't watch the video yet, but does it explain why you wouldn't also want the larger size in front for the same reason? Or do we just assume that, because less sidewall will naturally impact ride quality, they use the smaller wheel up front as a compromise to minimize that consequence?

As I write this, I wonder if we might see equal diameter wheels on the AWD models. Though, I think Porsche uses the unequal sizes on their both their RWD and AWD 911 models. And come to think of it, IIRC, the AWD G8x mules have been using the same wheels as the RWD cars.
I'd say, two times no:
1/ the rear-axle mainly needs to deal with the lateral forces for propulsion, but the front-axle (certainly in combo with AWD) only deals with transversal forces. A higher side wall on the front provides a more progressive behaviour on steer-in. I remember going to a driving course of BMW and the instructors learned me that I provoked understeer by being too aggressive on steer-in. The higher side wall helps to be more progressive and it uses the grip limits to determine the tightest corner and renders a cleaner traject with less understeer.
2/ In the AWD version, the front axle becomes also responsable for the propulsion. In this case a stiffer side-wall makes sense. But seen the weight distri (which will be worse for AWD) and the potential understeer behaviour, I would bet that M prefers the staggered combo.
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      01-17-2021, 04:57 PM   #101
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Quote:
Originally Posted by KoenG View Post
I'd say, two times no:
1/ the rear-axle mainly needs to deal with the lateral forces for propulsion, but the front-axle (certainly in combo with AWD) only deals with transversal forces. A higher side wall on the front provides a more progressive behaviour on steer-in. I remember going to a driving course of BMW and the instructors learned me that I provoked understeer by being too aggressive on steer-in. The higher side wall helps to be more progressive and it uses the grip limits to determine the tightest corner and renders a cleaner traject with less understeer.
2/ In the AWD version, the front axle becomes also responsable for the propulsion. In this case a stiffer side-wall makes sense. But seen the weight distri (which will be worse for AWD) and the potential understeer behaviour, I would bet that M prefers the staggered combo.
I agree with that, the only question mark is why the M5CS isn’t getting the staggered diameter. They are hunting Nordschleife records with that car and this seems like a simple/cheap/obvious solution if it helps with even half a second per lap. We haven’t seen the official M5CS specs yet though but nothing about staggered wheels has been mentioned.
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      01-17-2021, 05:09 PM   #102
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Quote:
Originally Posted by solstice View Post
I agree with that, the only question mark is why the M5CS isn’t getting the staggered diameter. They are hunting Nordschleife records with that car and this seems like a simple/cheap/obvious solution if it helps with even half a second per lap. We haven’t seen the official M5CS specs yet though but nothing about staggered wheels has been mentioned.
I believe it's a balancing excercise. You have to choose between 'wants' that are conflicting: and that is better behaviour for going into the turn: initiate it without too much understeer, and the second is maximum acceleration in the exit of the turn. I presume also that a pro driver would prefer a stiffer wheel on the front because he can better play/control the initiation phase, which I clearly couldn't The guys running nordschleife best times will be pro's and prefer stiffer and lower side walls.
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      01-17-2021, 05:18 PM   #103
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Quote:
Originally Posted by KoenG View Post
I believe it's a balancing excercise. You have to choose between 'wants' that are conflicting: and that is better behaviour for going into the turn: initiate it without too much understeer, and the second is maximum acceleration in the exit of the turn. I presume also that a pro driver would prefer a stiffer wheel on the front because he can better play/control the initiation phase, which I clearly couldn't The guys running nordschleife best times will be pro's and prefer stiffer and lower side walls.
Interesting points. Are you saying that the lower tire wall is ultimately faster in the hands of professional drivers and more tire wall is to help amateurs going faster? I so, are you talking AWD specifically or both RWD and AWD?

Cause I’m skeptical that BMW left any obvious advantage on the table when they designed the M4 GTS with staggered diameter. Of marketing reasons they needed the pros to post the quickest time as with the M5CS.
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      01-17-2021, 05:35 PM   #104
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Quote:
Originally Posted by solstice View Post
Interesting points. Are you saying that the lower tire wall is ultimately faster in the hands of professional drivers and more tire wall is to help amateurs going faster? I so, are you talking AWD specifically or both RWD and AWD?

Cause I’m skeptical that BMW left any obvious advantage on the table when they designed the M4 GTS with staggered diameter. Of marketing reasons they needed the pros to post the quickest time as with the M5CS.
An M4cs is RWD and the front axle doesn't have to bother with accelerative forces ==> best bias towards higher side walls since the potential time you lose in the first part of turn in, is not compensated with time gain in part 3 of the turn. An AWD on the other side "could" compensate it the exit phase of the turn!
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      01-17-2021, 05:39 PM   #105
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Originally Posted by KoenG View Post
An M4cs is RWD and the front axle doesn't have to bother with accelerative forces ==> best bias towards higher side walls since the potential time you lose in the first part of turn in, is not compensated with time gain in part 3 of the turn. An AWD on the other side "could" compensate it the exit phase of the turn!
That’s what I thought you meant, just wanted to be sure. With that in mind and if valid we could see the G8X AWD not using staggered diameter setup just as the M5CS. Sure will be interesting to see.
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      01-17-2021, 05:51 PM   #106
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Quote:
Originally Posted by solstice View Post
That’s what I thought you meant, just wanted to be sure. With that in mind and if valid we could see the G8X AWD not using staggered diameter setup just as the M5CS. Sure will be interesting to see.
Certainly! Chances for AWD are higher that front/rear uses the same diameter, but the weight distribution is also important. We'll probably move towards 55/45% and in this case, a higher side wall on the front is maybe still preferable. I presume what we discuss here is exactly the job of Frank in the video, still a bit disappointed he didn't go at all in this subject and only touched some generic specs of tires!
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      01-17-2021, 06:00 PM   #107
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They also mentionned that having a bigger air volume helps dissipate more heat. They also used bigger front calipers. The front is also heavier.

We often think one decision is to help one aspect but it's the fine equilibrium of all the small changes working together that produce the better results.
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      01-17-2021, 06:16 PM   #108
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Quote:
Originally Posted by PLF69 View Post
They also mentionned that having a bigger air volume helps dissipate more heat. They also used bigger front calipers. The front is also heavier.

We often think one decision is to help one aspect but it's the fine equilibrium of all the small changes working together that produce the better results.
Yes but having a higher/better heat dissipation is not sorted out I guess? Having a smaller wheel in front, and having tires with higher side walls better dissipate the heat... exactly how???
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      01-17-2021, 06:30 PM   #109
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Originally Posted by KoenG View Post
Certainly! Chances for AWD are higher that front/rear uses the same diameter, but the weight distribution is also important. We'll probably move towards 55/45% and in this case, a higher side wall on the front is maybe still preferable. I presume what we discuss here is exactly the job of Frank in the video, still a bit disappointed he didn't go at all in this subject and only touched some generic specs of tires!
I’ll again go back to the M5CS if indeed it doesn’t come with staggered diameter it has to be that it wasn’t any faster, with the ring record for sedans as target I can’t see them ignoring it if it was. The G8X AWD weight distribution is likely very similar to the F90.
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      01-17-2021, 06:53 PM   #110
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Quote:
Originally Posted by solstice View Post
I’ll again go back to the M5CS if indeed it doesn’t come with staggered diameter it has to be that it wasn’t any faster, with the ring record for sedans as target I can’t see them ignoring it if it was. The G8X AWD weight distribution is likely very similar to the F90.
Yes, when weight distribution between AWD versions are similar, and both use the same bias f/rwd and both have the same height of COG and share the same torsional stifness and have comparable wheelbase. But combine all this is exactly the job of Frank or not?
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