[flybigjet]

Gents-- a bit of help from the brain trust?

I need to know the *exact* differences between the Michelin Cup2's in 255/25/19 & 275/35/19 and Michelin Pilot Sport 4S's in the same size.

Long story short-- I like to track the car, but I ate through the stock PSS's in less than 8000 miles.

So, I got authorization from the Minister of War & Finance to get a separate wheelset and tires.

The car (2020 M2C) has 19" Apex EC-7's (half-inch wider than stock with appropriate M2C-specific offsets), MP4S 255/25/19 & 275/35/19 (+1 from stock), M-Performance coilovers and Millway Street camber plates installed. It's slightly lowered and has negative camber (I don't remember the numbers off the top of my head) dialed in both front and (slightly) rear to find a good balance between street and track. Everything above works great, is well-sorted and there's no contact or rubbing anywhere.

I've got an additional set of EC-7's in the garage and the goal is to be able to simply swap wheels/tires without having to muck with suspension settings, ride height, camber or spacers. (Yes, I know it's a compromise, but one I'm willing to live with considering how little free time I have in my life). Clearances are tight due to the wider wheels, wider tires and conical springs on the M-Performance coilovers.

I've seen pictures where the exact same size tire, exact same wheels in different tire lines from the same manufacturer look like they're almost an inch wider. That would be ...... bad as the clearance on this setup is VERY tight (Thanks, BMW).

So, I know it could be an issue, I know that there might be variance between the Cup2 and MP4S's, but I don't know where to deep dive to get *accurate* numbers. If it turns out that the Cup2's are significantly wider/taller, I'm a dead man since I have brand-new wheels sitting in my garage that I won't be able to use and my wife will flat-out kill me.

TIA, and Merry Merry.

R.

[Carrera2RS]

Are you running et 22 fronts or 28 ? assume 45 rear ?

I have et22 front and 45 rear with 3mm spacers and run 2.25F 2R camber with stock tyres loads of room, I think 255/275 will be a breeze

[flybigjet]

Originally Posted by Carrera2RS

Are you running et 22 fronts or 28 ? assume 45 rear ?

I have et22 front and 45 rear with 3mm spacers and run 2.25F 2R camber with stock tyres loads of room, I think 255/275 will be a breeze

The wheel specs are Front: 19x9.5, ET28, 22.65 lbs. & Rear: 19x10.5, ET45, 23.4 lbs.

The MP4S work perfectly in 255/275-19 as that's what's on the car at the moment.

The question is, will Cup-2's work in that size without having to add spacers or modify ride height and/or camber (mostly due to that damn conical spring BMW uses in the front.)

THAT'S the question I'm needing answered.

Fwiw as a side-note, the MP4S are much better than the stock Super Sports in 245/265. But with the Carbahn tune and M3/4 intake, I still break loose in 1st-4th gear without trying all that hard (in other words, the DSC goes nuts). And that's in CO with a hp loss due to altitude of about 15%.

R.

[flybigjet]

Tire Rack just emailed me this, but I'm not 100% sure how to interpret it for the information I need:

255/35/19 Pilot Sport 4S 26 " diameter/ Section width is 10.2" / Tread width is 8.2"/ Revs per mile 799 / weight 23#

255/35/19 Sport Cup 2 26" diameter/ Section width is 10.2 / Tread width is 9.1"/ Revs per mile 799/ weight 23#

275/35/19 Pilot Sport 4S 26.6" diameter/ Section width is 10.9/ Tread width is 9.8" / Revs per mile 783 / weight 27#

275/35/19 Sport Cup 2 26.6" diameter / Section width is 11.00 / Tread width is 9.5"/ Revs per mile 783/ weight 24#

[CSBM5]

I don't have your answer, but just wanted to mention that it's very hard to look at section width measurements to judge clearance. The reason is that section width is measured as a mounted tire's maximum girth essentially (on given wheel width which of course changes section width). What's not taken into account obviously is the profile of the sidewall that creates that maximum width.

Case in point where I got into this deeply was about 15 years ago switching from Hoosiers to BFG R1s. Same size tire, plenty of clearance with the Hoosier but massive rubbing with the R1. While the R1 did run wide for the size (I measured a section width of 276mm for a mounted 265/35-18 tire, and I even had it pinched a bit on an 8.5" wheel), but the sidewall profile on the R1 carries that section width all the way to the tread face (unlike most tires including the Hoosier which have a balloon shape to the sidewall that tapers from peak width to the tread face). Same issue hit me with my M5 a couple of years later switching from the NT-01 to the BFG R1 -- huge difference in clearance between two same size tires.

Note that the Cup2 is only available in the older design TW180 in those sizes, and those two sizes are only available in OE Mercedes specs (i.e. MO1 and MO) -- those design specs are even for two different Mercedes cars too.

If it was me and wanted to stick with Cup2s, I'd look at the new Cup2 Connect (TW240) which supposedly performs better than the older TW180 Cup2, and I'd go with 265/30-19 and 295/30-19 sizes. Those are replacement market designs as opposed to manufacturer specific specs too.

[CSBM5]

The measurement of tread width is a bit subjective and imprecise and is not something that Michelin provides. My understanding is that Tirerack themselves do that measurement.

[Carrera2RS]

If you have PS4S in the sizes you are considering PSC2's then YES they will work IMO, the larger 275 form tyre rack is quoted with an 11 rear. The size of the MPSS, PS4S and Cup2 are very, very similar

The highlighted yellow is not the tyre width but the tread width on a. 9" rim they all measure 10.2"

[flybigjet]

Originally Posted by CSBM5

If it was me and wanted to stick with Cup2s, I'd look at the new Cup2 Connect (TW240) which supposedly performs better than the older TW180 Cup2, and I'd go with 265/30-19 and 295/30-19 sizes. Those are replacement market designs as opposed to manufacturer specific specs too.

I'm adverse to going with the -30 series tires (which are recommended by Apex) for two reasons: 1. a -30 series sidewall in CO is a death sentence-- even if you're just going to/from the track, and 2. That fitment will definitely require spacers at a minimum according to Apex due to the conical front spring on the M-P coilovers.

It looks like the SC2-Connect's come in 255/275 in a 35/19 so that's good. And the extra tire wear (such as it is) is a nice bonus.

Query: Any experience with the whole "Connect" setup (sensors, magic box, App)? In other words-- is it worth springing for the setup since it looks like the CS2-Connect's are the way to go?

TIA--

R.

[Fabb]

Originally Posted by flybigjet

I'm adverse to going with the -30 series tires (which are recommended by Apex) for two reasons: 1. a -30 series sidewall in CO is a death sentence-- even if you're just going to/from the track, and 2. That fitment will definitely require spacers at a minimum according to Apex due to the conical front spring on the M-P coilovers.

It looks like the SC2-Connect's come in 255/275 in a 35/19 so that's good. And the extra tire wear (such as it is) is a nice bonus.

Query: Any experience with the whole "Connect" setup (sensors, magic box, App)? In other words-- is it worth springing for the setup since it looks like the CS2-Connect's are the way to go?

TIA--

R.

Not worth it. Just get a pyrometer

[Carrera2RS]

By the way if you want to check camber you can use a steel rule and a spirit level and average each axle if you are unsure of how flat the surface is. With 28F you will have zero problems with 255's on the outside. I have a tonne of room with 245 on et22's no clearance issues at all with no added camber, camber plates and now negative camber hubs (I disliked the NVH from Milway plates)

The area you should check is the inside I was tight with stock wheels, Litchfield suspension. So I couldn't have fitted 28 if I'd wanted to, stock wheel and tyre with Lichfield AST suspension

[Carrera2RS]

By the way I will be going to 255/275 when I need replacement tyres and I dont think there will be any make of 255 I won't be able to fit with et22, given Apex recommend 265/30 on et28 and you have camber plates Im not sure which bit go the tyre your concerned about ?

You could also phone Michelin technical if there is a rogue tyre that is a bit wider, which is highly unlikely between the PS4S, PSS, PSC2

[COChris]

For what it's worth, I run a 19x9.5 et28 wheel up front with a 265/30 Michelin PS4S and have no trouble with rubbing on street or track. I tend to daily the car, but do avoid taking it on some roads in the Denver Metro area. I understand your fear of shredding a tire or bending a wheel given some road surfaces available to us.

FYI: This is with OEM camber, caster, and toe. Hope that helps.

Chris