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

[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.

[FourPtDrift]

Here are some side by side comparison pics of the OE Star Spec Michelin SuperSports in 265/30r20 and 285/30r20 next to the new Michelin PS4S in 275/30r20 and 295/30r20.

Please note the OE tires were photographed while still mounted on the Type 666 rims, hence the slight difference in perceived OD.

The difference in contact patch between OE StarSpec sizing and the standard sizing on the larger PS4S’ is MUCH more than the 10mm in unit size would suggest and is clearly visible in the photos. An absolutely fantastic upgrade - worth doing, without a doubt.

[uniqueMR]

Beautiful. It looks nice.
Do you have any pics from rear of the car?

Also, 275 f and 295 r increased car height?

[FourPtDrift]

Originally Posted by uniqueMR

Beautiful. It looks nice.

Thank you! I couldn’t be happier with how the combination of the rims, tires and ride height worked out. And the performance has increased considerably.

Do you have any pics from rear of the car?

No, but I’ll see if I can post something later.

Also, 275 f and 295 r increased car height?

Empirically, yes. There is a very small, essentially imperceptible increase. However, you need to remember that the Star Spec tread width is about 10mm narrower than a standard sized tire of the same aspect ratio. So, moving up by 10mm on a standard sized tire returns a net increase of about 20mm per tire or essentially 40mm across each axle. This is a massive gain on the same OE rims with no penalities, no variance from front to rear or impact to the car’s electronics and ride control services. Consider this, our F82 with the M Performance HAS kit and the up-sized PS4S tires on 666 rims sits noticeably lower than our F83 with OE SuperSports and ZCP suspension, also on 666 rims.

Hope this info helps!

[pbar]

Looks great, and I'm sure the straight line traction is much improved.

Have you noticed any differences in cornering? (I read that BMW likes to stretch tires on M cars so there's less sidewall roll)

[moonluv810]

Sorry for the stupid question. What is star spec?

[Jaymax85]

Originally Posted by moonluv810

Sorry for the stupid question. What is star spec?

Bmw specific tire

[55Fisher]

Originally Posted by Jaymax85

Bmw specific tire

Do you have spacers on too?

Finally someone has done what everyone has been talking about! Thank you.

[Ilikemike]

Originally Posted by FourPtDrift

Here are some side by side comparison pics of the OE Star Spec Michelin SuperSports in 265/30r20 and 285/30r20 next to the new Michelin PS4S in 275/30r20 and 295/30r20.

Please note the OE tires were photographed while still mounted on the Type 666 rims, hence the slight difference in perceived OD.

The difference in contact patch between OE StarSpec sizing and the standard sizing on the larger PS4S’ is MUCH more than the 10mm in unit size would suggest and is clearly visible in the photos. An absolutely fantastic upgrade - worth doing, without a doubt.

Really well organized and presented!

[FourPtDrift]

Originally Posted by pbar

Looks great, and I'm sure the straight line traction is much improved.

Considerably! And the car is much "pointier" from center, as well. Hook-up, greatly improved - an absolute must before any tuning to the car.

Have you noticed any differences in cornering? (I read that BMW likes to stretch tires on M cars so there's less sidewall roll)

Yes - that's really a myth. What BMW wants to do is mitigate liability by dialing in understeer. The OE aspect ratio does exactly that.

The PS4S has an extremely strong side wall and the turn in with my 275/30r20 fronts is fantastic. Excellent communication to the fingertips and butt.

Can't say it enough - this is how the car should have been setup from the start.

[FourPtDrift]

Originally Posted by 55Fisher

Do you have spacers on too?

Nope, no spacers. Spacers - not a good idea. Huge performance consequences. My changes, while aesthetically pleasing, are intended for functional improvement. Yes, to be certain, swapping to an 18" rim would be an even greater functional improvement, but I'm looking for balance between intended design (and I love the two-tone finish of my Type 666 rims) while maximizing performance.

Finally someone has done what everyone has been talking about! Thank you.

You're very welcome - what you wrote is why I made the post. I saw lots of back and forth online regarding this issue, so I did my own research, found what I think is absolutely the best tuning shop in the SF Bay Area (BR Racing is the REAL deal - they turn out real race cars on a regular basis - I'm talking everything from Cup cars to LeMans Prototypes and everything in between) and pulled the trigger. The results are perfect. And with VF Engineering's Stage 1 - the car is absolutely a beast.

[FourPtDrift]

Originally Posted by Ilikemike

Really well organized and presented!

Thank you!

[uniqueMR]

Originally Posted by FourPtDrift

Thank you! I couldn’t be happier with how the combination of the rims, tires and ride height worked out. And the performance has increased considerably.



No, but I’ll see if I can post something later.



Empirically, yes. There is a very small, essentially imperceptible increase. However, you need to remember that the Star Spec tread width is about 10mm narrower than a standard sized tire of the same aspect ratio. So, moving up by 10mm on a standard sized tire returns a net increase of about 20mm per tire or essentially 40mm across each axle. This is a massive gain on the same OE rims with no penalities, no variance from front to rear or impact to the car’s electronics and ride control services. Consider this, our F82 with the M Performance HAS kit and the up-sized PS4S tires on 666 rims sits noticeably lower than our F83 with OE SuperSports and ZCP suspension, also on 666 rims.

Hope this info helps!

Thanks much. Great info

[pbar]

Originally Posted by FourPtDrift

Nope, no spacers. Spacers - not a good idea. Huge performance consequences. My changes, while aesthetically pleasing, are intended for functional improvement. Yes, to be certain, swapping to an 18" rim would be an even greater functional improvement, but I'm looking for balance between intended design (and I love the two-tone finish of my Type 666 rims) while maximizing performance.

Doesn't look like you have camber plates either from the photo?

I've also been thinking of picking up an 18" Apex setup for track, since the 20" rims and PSS were a bit of a handful last time (really hard to keep the temperatures/pressures sensible). Would be interested to hear feedback on the PS4S

Originally Posted by FourPtDrift

You're very welcome - what you wrote is why I made the post. I saw lots of back and forth online regarding this issue, so I did my own research, found what I think is absolutely the best tuning shop in the SF Bay Area (BR Racing is the REAL deal - they turn out real race cars on a regular basis - I'm talking everything from Cup cars to LeMans Prototypes and everything in between) and pulled the trigger. The results are perfect. And with VF Engineering's Stage 1 - the car is absolutely a beast.

Will have to check out BR Racing! (Quite close to work). How are their prices?

[shay2nak]

When you say "standard drop" you mean the BMW recommended height? So there's still room to lower the front?

[FourPtDrift]

Originally Posted by uniqueMR

Thanks much. Great info

Quite welcome - hope it helps.

Originally Posted by pbar

Doesn't look like you have camber plates either from the photo?

No. Camber plates are great for regular track use but are a big no-no on the street. Camber plates and road-crown simply do not mix well. Now, if you do track on a regular basis, are going to go with an R compound tire on an 18" rim, dialing in the extra camber via camber plates can be advantageous - but then you'll have to reset for going back to street use. What may work exceedingly well on a track surface (that doesn't have road-crown) can be downright dangerous on a public road.

I've also been thinking of picking up an 18" Apex setup for track, since the 20" rims and PSS were a bit of a handful last time (really hard to keep the temperatures/pressures sensible). Would be interested to hear feedback on the PS4S

I have yet to track them but from those who have and had previously run PSS, the general consensus is that the PS4S is a major improvement. Your comments on keeping consistent tire pressure seems like it might be more of a progression issue on driving technique - tough to say as I haven't watched you drive on track. But generally speaking, smooth driving which = fast driving also = consistent pressures/temperatures. Where were you on track and what time of year?

Will have to check out BR Racing! (Quite close to work). How are their prices?

Extremely reasonable. It is a father and son team and they've been at it for a very long time. The day I was there they were working on two Porsche GT3's, an LMP3 car and a customer just showed up with a McLaren 720. They also had in the garage. Mini, a BMW 2002, and a Cayman GT4. Needless to say I felt very comfortable with them.

Be sure to tell them Daniel with the White M4 sent you...

Originally Posted by shay2nak

When you say "standard drop" you mean the BMW recommended height? So there's still room to lower the front?

Yes - that's right, the recommended height. And while the car could be lowered further - unless you're going for some sort of aesthetic gain, the performance would only suffer. Lowering a car beyond a certain point where the control arms have an optimum position for movement only hinders performance. I wouldn't change the height of my car not for aesthetics (I think it looks perfect at that height) nor for performance reasons (it is truly dialed in right and performance would only decrease with any changes).

[einscot]

looking at tire rack shows two different 295/30/20 sizes, do you happen to know which one your shop used? considering doing both the M Perf HAS and the size up with PS4S as my tires will need replacing in the next few months.

[pbar]

Originally Posted by FourPtDrift

I have yet to track them but from those who have and had previously run PSS, the general consensus is that the PS4S is a major improvement. Your comments on keeping consistent tire pressure seems like it might be more of a progression issue on driving technique - tough to say as I haven't watched you drive on track. But generally speaking, smooth driving which = fast driving also = consistent pressures/temperatures. Where were you on track and what time of year?

Good to know!

The last time I had the 20" PSS on the track was ThunderHill in June 2017. It was 110F in the shade ... and I had to end the day early due to a drivetrain malfunction (which turned out to be the exhaust temps had exceeded 550C - over 1000F! - which caused the high-pressure fuel pump to shut down). Here's a video from that day

- I don't think I was overdriving *too* much , but the tires and brakes were definitely harder to manage than normal. With my previous M4 (on 19's) I found it a lot easier to dial in the pressures.

Originally Posted by FourPtDrift

Extremely reasonable. It is a father and son team and they've been at it for a very long time. The day I was there they were working on two Porsche GT3's, an LMP3 car and a customer just showed up with a McLaren 720. They also had in the garage. Mini, a BMW 2002, and a Cayman GT4. Needless to say I felt very comfortable with them.

Be sure to tell them Daniel with the White M4 sent you...

Will do!

(Getting a little off-topic, sorry....)

[uniqueMR]

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

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

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

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.

[FourPtDrift]

Originally Posted by einscot

looking at tire rack shows two different 295/30/20 sizes, do you happen to know which one your shop used? considering doing both the M Perf HAS and the size up with PS4S as my tires will need replacing in the next few months.

The tirerack.com page on the PS4S is a tricky read. Forget about the "size" tab and skip to the "specs" tab. Now you'll be able to note there is a difference where one 295/30r20 is marked as an MO spec (Mercedes-Benz OE) and another is just a "generic." You'll note that the non-MO spec tire (which is what I have has a significantly wider tread width - even those the section wide is essentially the same. That's what you'll want to get.

As an FYI - I purchased from America's Tire - love their warranty. Best in the business and most convenient for me if and when I need to call in on the warranty for an emergency replacement.

[FourPtDrift]

Originally Posted by pbar

Good to know!

The last time I had the 20" PSS on the track was ThunderHill in June 2017. It was 110F in the shade ...

I don't think I'd want to do anything with 110F in the shade temps... good on you for sticking it out and getting on track.

and I had to end the day early due to a drivetrain malfunction (which turned out to be the exhaust temps had exceeded 550C - over 1000F! - which caused the high-pressure fuel pump to shut down).

I've been eyeing the VF Engineering cooling solutions and I suspect that if I'm going to be hitting Thermal or Thunder in the heat - I may add some extra chilling capability beforehand. I've done my time with overheating on track days with an N54 and am not interested in ever repeating those experiences...

Here's a video from that day

- I don't think I was overdriving *too* much , but the tires and brakes were definitely harder to manage than normal. With my previous M4 (on 19's) I found it a lot easier to dial in the pressures.

Great in-car video and fun chatting with you about it offline. For those curious about my comments - PBAR is certainly very smooth - probably the most important skill to master - but absent telemetry, I'd say I detect either a bit more weight transfer activity going on than necessary. A little less brake, a bit more trailing throttle and more progressive throttle into corners results in faster exits, and less pressure/heat plumes before the apex. All around, track times will improve and temps will be more consistent.

Will do!

(Getting a little off-topic, sorry....)

All good - and all enjoyed!