275/30r20 and 295/30r20 PS4S on Type 666 with M Performance HAS

[FourPtDrift]

Originally Posted by uniqueMR

Silly question: is there any tire rubbing? Even with extreme turning of the wheel while driving or standing still.

Nope. None at all Perfect fit.

[FourPtDrift]

Originally Posted by cca101

I really like how these sizes sit on the rims. I saw PS4's with stock sizes on 666 rim at the dealer and there was almost no rim protection.

Agreed. That's what happens when you stretch a tire, you pull the bead away from the rim lip, effectively neutering it of its purpose. BMW's practice of placing under-sized tired has been going on ever since side walls started dipping down below 40 series heights. The claims about "faster turn-in" are absolute nonsense. This is liability mitigation, pure and simple. Lower the contact patch and you dial-in understeer on the front and create a false "illusion" of muscle car oversteer on the rear. Nevermind the fact that the car is a.) unbalanced, b.) the rims are left completely unprotected and c.) removing a vertical side wall removes the first key element of "suspension communication" to the driver.

These look like they stick out a good 1/4in from the edge, looks nice.

You're pretty close - I'd say it looks RIGHT.

Do you know of any advantage of trying these sizes but M01 Mercedes specs?

The Mercedes-Benz spec tire has a narrower tread width - total waste of time. Also, all manufacturer spec tires (Star, N, MO, etc.) vary not just on tread width but on other elements such as toe wrap and even sometimes, compound. The best way to go when picking up up-sized PS4S tires for our cars is to go with the "generic" variety.

Also these tires weigh quite a bit more than the stock ones, 3 lbs each? I'm sure the grip benefit far outweighs the added inertial weight.

I am sure that what I've put on weighs more than what I took off - after all I have added more rubber - but not THAT much more. As for feeling the added weight? Nope. Not at all. Do I feel the added grip, turn-in and all around performance gain? Oh, yeah! You betchya!

[cca101]

Originally Posted by FourPtDrift

Agreed. That's what happens when you stretch a tire, you pull the bead away from the rim lip, effectively neutering it of its purpose. BMW's practice of placing under-sized tired has been going on ever since side walls started dipping down below 40 series heights. The claims about "faster turn-in" are absolute nonsense. This is liability mitigation, pure and simple. Lower the contact patch and you dial-in understeer on the front and create a false "illusion" of muscle car oversteer on the rear. Nevermind the fact that the car is a.) unbalanced, b.) the rims are left completely unprotected and c.) removing a vertical side wall removes the first key element of "suspension communication" to the driver.



You're pretty close - I'd say it looks RIGHT.



The Mercedes-Benz spec tire has a narrower tread width - total waste of time. Also, all manufacturer spec tires (Star, N, MO, etc.) vary not just on tread width but on other elements such as toe wrap and even sometimes, compound. The best way to go when picking up up-sized PS4S tires for our cars is to go with the "generic" variety.



I am sure that what I've put on weighs more than what I took off - after all I have added more rubber - but not THAT much more. As for feeling the added weight? Nope. Not at all. Do I feel the added grip, turn-in and all around performance gain? Oh, yeah! You betchya!

I trust your judgment, but if I start losing crucial roll races because of the extra 6 pounds the engine has to spin in the rear i'm going to be upset

[TTR]

What is sense to buy HAS, in eur it's cost 1700 eur and KW ClubSport 3 Way Cost 3300eur

[FourPtDrift]

Originally Posted by cca101

I trust your judgment, but if I start losing crucial roll races because of the extra 6 pounds the engine has to spin in the rear i'm going to be upset

I'd say the extra contact patch will get you going faster before the weight could ever slow you down. BUT - if you lose a run - I'll buy you a coke and a large fries to make you feel better.

[FourPtDrift]

Originally Posted by TTR

What is sense to buy HAS, in eur it's cost 1700 eur and KW ClubSport 3 Way Cost 3300eur

KW is one of the finest suspension component manufactures on the planet. No doubt about it. I know the company and the people within it, personally.

Having said that, committing to a ClubSport with 20" rims and street performance tires makes NO sense whatsoever - additionally, I value my EDC control which I lose with the KW solution. THIS is why I didn't go the ClubSport way with my F82.

In my estimation, for an F82, running Type 666 rims and street tires, there is no better solution than the BMW M Performance HAS kit.

[TTR]

Originally Posted by FourPtDrift

KW is one of the finest suspension component manufactures on the planet. No doubt about it. I know the company and the people within it, personally.

Having said that, committing to a ClubSport with 20" rims and street performance tires makes NO sense whatsoever - additionally, I value my EDC control which I lose with the KW solution. THIS is why I didn't go the ClubSport way with my F82.

In my estimation, for an F82, running Type 666 rims and street tires, there is no better solution than the BMW M Performance HAS kit.

For stock - yes, i wen to 19 from 20 666 zcp

[bringbacklsb]

Originally Posted by FourPtDrift

There are a few threads covering PS4S.

There are a few threads covering sizing up on Type 666 rims.

And there are questions about making all the above fit with a drop from an M Performance HAS kit.

And there are some random images that cover a little bit of each.

Well, I've purchased new Michelin PS4S in 275/30r20 and 295/30r20 for my Type 666 rims on my F82 which is equipped with a standard drop via BMW M Performance HAS kit, and felt some photos might be helpful for those wondering how it all comes together.

And how does it all feel? AMAZING. An absolutely essential mod - HIGHLY recommended.

Great info! What would be the disadvantage of going with a 305 width tire on the rear? Is it that the electronics would be thrown off, rubbing on the rear, or both? I know some have put 305s on but you went with the 295s, so what was the reason behind this? Thanks!

[FourPtDrift]

Originally Posted by bringbacklsb

Great info! What would be the disadvantage of going with a 305 width tire on the rear? Is it that the electronics would be thrown off, rubbing on the rear, or both? I know some have put 305s on but you went with the 295s, so what was the reason behind this? Thanks!

Well, the first question is - what size rim? If you're going with the Type 666 rim, there is no good reason why you'd want go larger than 295/30.

1.) A 285/30 on the rear Type 666 is "stretched," meaning that the sidewall is slanted towards the wheel well. This produces a smaller contact patch and very little active suspension communication to the driver as to what the car is doing as weight is transferred from corner to corner.

2.) A 295/30 on the rear Type 666 is "normal," meaning that the side wall is perpendicular to the road surface. This produces an optimum amount of contact patch while improving communication to the driver during weight transfer movements. Hint: take a look at racing tires - F1, Indy, DTM, etc., etc., what do the side walls look like?

3.) A 305/30 on the rear of a Type 666 would "bulge" meaning the side wall would extend away from the body of the car. The contact patch would not increase appreciably because the bulging sidewall would result in a warping of the contact patch. Furthermore, this bulge would also result in an increase in the OD and circumference measurement of the tire which would require a comparable increase in the front tire to maintain rotational equilibrium front to back. Rubbing would certainly happen and performance would most certainly fall off as increase tire size beyond spec is equivalent to up gearing the car.

If you want a 305 series tire- the F80/F82/F83 wheel well will accommodate it, but you'll need a different rim - its not going to happen on the Type 666.

Hope this info helps...

-Daniel

[FourPtDrift]

Originally Posted by TTR

For stock - yes, i wen to 19 from 20 666 zcp

Well, the moment you decided to go back down to a 19" rim from a 20" to increase performance, all bets are off. The first question I'd ask you is why not just go to an 18" setup? Technically, if you're trying to go for a pure track setup, and you don't have ceramic brakes, the best solution would probably be an 18" rim setup with a 305 or even 315 rear.

-Daniel

[bringbacklsb]

Originally Posted by FourPtDrift

Well, the first question is - what size rim? If you're going with the Type 666 rim, there is no good reason why you'd want go larger than 295/30.

1.) A 285/30 on the rear Type 666 is "stretched," meaning that the sidewall is slanted towards the wheel well. This produces a smaller contact patch and very little active suspension communication to the driver as to what the car is doing as weight is transferred from corner to corner.

2.) A 295/30 on the rear Type 666 is "normal," meaning that the side wall is perpendicular to the road surface. This produces an optimum amount of contact patch while improving communication to the driver during weight transfer movements. Hint: take a look at racing tires - F1, Indy, DTM, etc., etc., what do the side walls look like?

3.) A 305/30 on the rear of a Type 666 would "bulge" meaning the side wall would extend away from the body of the car. The contact patch would not increase appreciably because the bulging sidewall would result in a warping of the contact patch. Furthermore, this bulge would also result in an increase in the OD and circumference measurement of the tire which would require a comparable increase in the front tire to maintain rotational equilibrium front to back. Rubbing would certainly happen and performance would most certainly fall off as increase tire size beyond spec is equivalent to up gearing the car.

If you want a 305 series tire- the F80/F82/F83 wheel well will accommodate it, but you'll need a different rim - its not going to happen on the Type 666.

Hope this info helps...

-Daniel

It helps tremendously Daniel! What if one were to change those rims over to an HRE or BBS, and purchase a wider rim. Do you know what the optimum rim width and tire sizes would be (assuming one wanted 305 on the rear) in such a situation? I presume that you could not use 305 even on aftermarket rims without spooking the electronics because the front tire size could not be upgraded any further due to rubbing?

[FourPtDrift]

Originally Posted by bringbacklsb

It helps tremendously Daniel!

Good, then we're getting somewhere.

What if one were to change those rims over to an HRE or BBS, and purchase a wider rim.

Wider rims, mean opportunity for wider tires - so long as the tire, at a given sectional width and at a specific OD (outer diameter) will fit within the fender liner within the wheel well/fender.

Do you know what the optimum rim width and tire sizes would be (assuming one wanted 305 on the rear) in such a situation?

Depends on the exact model of rim and the exact model of tire at that size for that rim. Different tires of the same aspect ratio will have different measurements.

Sadly, too many drivers and yes, even "professionals" simply throw around makes and models of tires and rims and slap them together thinking they've put together a winning solution and they haven't. To the extent they're after a "look" and they're happy with the "look," well then, good on them. But that doesn't mean they've produced a superiorly performing solution.

I think you need to first clearly figure out what you're trying to accomplish - how the car is going to be driven and then figure out who is going to put it together for you. If you can fill in some variables, I can try to give you some more direction.

I presume that you could not use 305 even on aftermarket rims without spooking the electronics because the front tire size could not be upgraded any further due to rubbing?

No. Theoretically you could get a 285 on the front, but that's not the issue. The problem you're talking about has nothing to do with the width of the tire, but rather the HEIGHT of the tire. The distance from the center of the axel to the road surface needs to be the same on the front and back of the car. Consider cars that have 19" front rims and 20" rear rims - the aspect ratio varies on these cars front and rear tires such that the front tire is TALLER than the rear tire to keep circumference (and of course, the outer diameter) the same from front to back. Aspect ratio changes only when rim width changes.

Do you have a good tuning shop? They should be walking you through this process. Send me some more details and I'll see what blanks I can fill in for you.

[martial]

FourPtDrift noob question but will this tire set up work without lowering ie stock height. thanks in advance!

[FourPtDrift]

Originally Posted by martial

FourPtDrift noob question but will this tire set up work without lowering ie stock height. thanks in advance!

Absolutely. In fact, I intend to swap out the 265/30r20 front and 285/30r20 rear SuperSports on our F83 which runs a "normal" ZCP suspension setup (no HAS kit) with the same 275/30r20 front and 295/30r20 rear PS4S setup as our F82.

[bringbacklsb]

Originally Posted by FourPtDrift

Good, then we're getting somewhere.



Wider rims, mean opportunity for wider tires - so long as the tire, at a given sectional width and at a specific OD (outer diameter) will fit within the fender liner within the wheel well/fender.



Depends on the exact model of rim and the exact model of tire at that size for that rim. Different tires of the same aspect ratio will have different measurements.

Sadly, too many drivers and yes, even "professionals" simply throw around makes and models of tires and rims and slap them together thinking they've put together a winning solution and they haven't. To the extent they're after a "look" and they're happy with the "look," well then, good on them. But that doesn't mean they've produced a superiorly performing solution.

I think you need to first clearly figure out what you're trying to accomplish - how the car is going to be driven and then figure out who is going to put it together for you. If you can fill in some variables, I can try to give you some more direction.



No. Theoretically you could get a 285 on the front, but that's not the issue. The problem you're talking about has nothing to do with the width of the tire, but rather the HEIGHT of the tire. The distance from the center of the axel to the road surface needs to be the same on the front and back of the car. Consider cars that have 19" front rims and 20" rear rims - the aspect ratio varies on these cars front and rear tires such that the front tire is TALLER than the rear tire to keep circumference (and of course, the outer diameter) the same from front to back. Aspect ratio changes only when rim width changes.

Do you have a good tuning shop? They should be walking you through this process. Send me some more details and I'll see what blanks I can fill in for you.

I don't even have the car yet, but am planning ahead. I would like to have the most optimum performance that a 20" wheel offers, and the larger back tire is specifically to try and maximize traction on acceleration. So, if I stay with the 666 wheels, I would just do the exact setup you've recommended as the best approach. But, if I decide that I prefer the HRE P101 wheels and wanted to try and fit a 305 on the back (presumably the widest I could go), what would be the proper width rim and tire size/brand combination for that particular setup (that would not adversely impact electronics)?

[whoop_ass]

Originally Posted by FourPtDrift

Agreed. That's what happens when you stretch a tire, you pull the bead away from the rim lip, effectively neutering it of its purpose. BMW's practice of placing under-sized tired has been going on ever since side walls started dipping down below 40 series heights. The claims about "faster turn-in" are absolute nonsense. This is liability mitigation, pure and simple. Lower the contact patch and you dial-in understeer on the front and create a false "illusion" of muscle car oversteer on the rear. Nevermind the fact that the car is a.) unbalanced, b.) the rims are left completely unprotected and c.) removing a vertical side wall removes the first key element of "suspension communication" to the driver.



You're pretty close - I'd say it looks RIGHT.



The Mercedes-Benz spec tire has a narrower tread width - total waste of time. Also, all manufacturer spec tires (Star, N, MO, etc.) vary not just on tread width but on other elements such as toe wrap and even sometimes, compound. The best way to go when picking up up-sized PS4S tires for our cars is to go with the "generic" variety.



I am sure that what I've put on weighs more than what I took off - after all I have added more rubber - but not THAT much more. As for feeling the added weight? Nope. Not at all. Do I feel the added grip, turn-in and all around performance gain? Oh, yeah! You betchya!

Great thread, great advice.
but here is the thing, the 666 wheels share the same offset as the 437 just an inch bigger. I am running P4S 265/35 19" so one size up from the stock size and damn I am very close to the wheel touching the strut with my MP HAS kit, you have to be running spacer to fit a 275 on the front?

also one thing it is known that with a bit of a stretched tyre translates to less flex and more feedback, have a look at the GT3 it runs a 12" rear rim with a 305 rubber the N0 spec pilot sport cup2 has a tread width of 12.1 and a sectional width of 12.3, there has to be a reason for this.

I am planning to get some 20" wheels as well and looking at doing a 275 P4s and a 305 rear on 11" rim personally i would prefer it to sit on an 11.5" rear but the rim I have opted for is 11" with ET40 so hopefully will work no problem.

JamesGames has made a great suggestion as well for cup 2's 245/35 20" N0 porsche fitment with a 295/30 rear.
the only thing I am not happy about is that the front is 26.8" overall diameter and the rear is 27". It technically should be paired with a 305 rear with OD of 27.2"

check how close I am with no spacers with a 265/35 19" PS4.

[CarbonFoot]

^^Hard to tell from the angle, but certainly doesn't look like a lot of clearance. Wonder what the OPs clearance looks like with his setup and M Perf HAS.

[pbar]

Originally Posted by whoop_ass

check how close I am with no spacers with a 265/35 19" PS4.

That photo looks like the shoulder of the tire has been rubbing?

[whoop_ass]

Ye the angle is a bit hard to see and looks exaggerated a bit.
Its def not rubbing got about 5mm from tire shoulder to MP HAS strut. I will try get another photo from a different angle.
With a 275 it will be even worse due to the wider sectional width of a 275.

found a better pic from different angle

[FourPtDrift]

Originally Posted by bringbacklsb

I don't even have the car yet, but am planning ahead. I would like to have the most optimum performance that a 20" wheel offers, and the larger back tire is specifically to try and maximize traction on acceleration.

For what purposes? Road courses? Drag strip?

So, if I stay with the 666 wheels, I would just do the exact setup you've recommended as the best approach. But, if I decide that I prefer the HRE P101 wheels and wanted to try and fit a 305 on the back (presumably the widest I could go),

Honestly, I don't know. I suspect you're probably right.

what would be the proper width rim and tire size/brand combination for that particular setup (that would not adversely impact electronics)?

No, I can't imagine it wouldn't create an issue as the height of the rubber would be the same.

[FourPtDrift]

Originally Posted by whoop_ass

Great thread, great advice.
but here is the thing, the 666 wheels share the same offset as the 437 just an inch bigger. I am running P4S 265/35 19" so one size up from the stock size and damn I am very close to the wheel touching the strut with my MP HAS kit, you have to be running spacer to fit a 275 on the front?

No spacers - no rubbing. Your aspect ratio to my aspect ratio is essentially the same outer dimension considerations, the difference of course is your tire is 0.5" taller around the rim. Essentially, the real variable is going to be the amount of drop from the HAS kit - which since mine was done pre-delivery by a dealer out of state, I really didn't get much in the way of empirical data from the install process. But the photographs pretty much show - the drop is VERY conservative.

[QUOTE] also one thing it is known that with a bit of a stretched tyre translates to less flex and more feedback,

Well, that's not an absolute. Certainly when dealing with a relatively soft side wall, stretching the tire will produce FASTER response (which also translates to a much steeper slip angle, too - not necessarily a desirable attribute), but that doesn't mean that a normal sidewall, perpendicular to the road surface is any less communicative. And with an exceptionally high quality tire (such as the PS4S) you're going to get a side wall that works as it should, as part of the suspension system. And then there's the increased contact patch, too...

have a look at the GT3 it runs a 12" rear rim with a 305 rubber the N0 spec pilot sport cup2 has a tread width of 12.1 and a sectional width of 12.3, there has to be a reason for this.

Yes. For the same reason that the GTS RS ends up with a 325 series tire with a section width of 13.6" and tread width of 13" - and yes, its all about the different intended driver and different expected driving style and performance considerations.

The 305 tire is going to keep the LESS frenetic GT3 dependant upon throttle oversteer for rotation - just as the GT3 RS - but it's going to do it at lower speeds and with lower power input requirements. The GT3 RS is targeted at a different driver, different environment and is working with a significantly higher performance threshold. Its tires are NOT stretched and furthermore, they're significantly wider. At the end of the day, its the high performing solution - but perhaps not the livlier solution.

I am planning to get some 20" wheels as well and looking at doing a 275 P4s and a 305 rear on 11" rim personally i would prefer it to sit on an 11.5" rear but the rim I have opted for is 11" with ET40 so hopefully will work no problem.

I suspect that will work.

JamesGames has made a great suggestion as well for cup 2's 245/35 20" N0 porsche fitment with a 295/30 rear.

If you gave me the tires for free I wouldn't run them on a daily driver - at least not for my application. At any dollar amount, I don't think I could have a better solution than what I have on now. As great as cup's are - I don't think I'd want to drive up and over the grapevine or through the central valley while it was rainining with them on - and had a trunk full of whatever I was traveling with - no way.

the only thing I am not happy about is that the front is 26.8" overall diameter and the rear is 27". It technically should be paired with a 305 rear with OD of 27.2"

Also something that is no bueno with that approach.

check how close I am with no spacers with a 265/35 19" PS4.

Close - but - again - unknown variable in variance in drop between your car and mine.

And - it still fits.

[FourPtDrift]

Originally Posted by CarbonFoot

^^Hard to tell from the angle, but certainly doesn't look like a lot of clearance. Wonder what the OPs clearance looks like with his setup and M Perf HAS.

That's an interesting question - I'll see if I can get a photo.