[mr_lab_rat]

And the most important question - are they square or staggered?

The reason I'm asking is that I got aftermarket square setup (not from the dealer) and it's causing traction control issues. I'm expecting the dealer to blame my square setup so I'm trying to find out if BMW will actually sell square winter sets to M2 owners.

[MetalMK]

No, the 640M and 641M are also staggered. Ex. 640M has the size of 235/40-18 and 255/35-18.

However, the traction control should not cause a problem if you give it some time. What do you mean by "issues"?

[mr_lab_rat]

Originally Posted by MetalMK

No, the 640M and 641M are also staggered. Ex. 640M has the size of 235/40-18 and 255/35-18.

However, the traction control should not cause a problem if you give it some time. What do you mean by "issues"?

The traction control interferes with acceleration. Cruising at 70mph, 6th gear. When I step on it the TCS kicks in and stops me from accelerating. At those speeds it's not wheelspin, it's a TCS malfunction.

I believe it comes from the square setup. The TCS is used to the rear wheels being about 2% taller so they spin slower compared to the fronts. When the wheel speed is the same front and rear the TCS might see it as rear wheels slipping.

That's what's happening to me (2017 car with old software). I'm getting the software updated to see if it helps.

[MetalMK]

Originally Posted by mr_lab_rat

The traction control interferes with acceleration. Cruising at 70mph, 6th gear. When I step on it the TCS kicks in and stops me from accelerating. At those speeds it's not wheelspin, it's a TCS malfunction.

I believe it comes from the square setup. The TCS is used to the rear wheels being about 2% taller so they spin slower compared to the fronts. When the wheel speed is the same front and rear the TCS might see it as rear wheels slipping.

That's what's happening to me (2017 car with old software). I'm getting the software updated to see if it helps.

That is concerning. I know that stock rear wheels are taller than the front, but some people run square setups on the track and they have no issues with traction control.

I have a square winter setup myself but I have no installed it yet due to the rain. Our Canadian cars do not have TPMS, so did you reset your flat tire monitor? I read somewhere that FTM can help the car adapt to a square setup.

[mr_lab_rat]

Originally Posted by MetalMK

That is concerning. I know that stock rear wheels are taller than the front, but some people run square setups on the track and they have no issues with traction control.

I have a square winter setup myself but I have no installed it yet due to the rain. Our Canadian cars do not have TPMS, so did you reset your flat tire monitor? I read somewhere that FTM can help the car adapt to a square setup.

I have seen only one occurrence where someone had DSC troubles with track tires. There is a good chance that people who go for square track setup are running without DSC though.

I wouldn't worry too much, if it was a real issue it would come up in the forums a lot. I think I just got unlucky with the old software and really soft tires (Blizzak WS80).

[mr_lab_rat]

Update: Of course they blamed the tires They offered me a lovely $4200 deal on staggered winter set.

[HazChem]

I bought 641M set and while the wheels are staggered, the tires are square at 335/35/19. First thing I did was to reset the TPMS and haven’t had any issues at any speed.

[mr_lab_rat]

Originally Posted by HazChem

I bought 641M set and while the wheels are staggered, the tires are square at 335/35/19. First thing I did was to reset the TPMS and haven’t had any issues at any speed.

Funny thing is that they said the OEM specs for winter tires are 235/40/18 and 255/35/18. That makes the rear tire diameter smaller than the front so I really don't see how that would make things better. I'll reset the TPMS and see how it goes.

[HazChem]

Bummer. I got mine from a BMW dealer and this was the set up they said BMW recommended for the M2C.

[tux2005]

I didn't buy my square winter tire setup from a dealership, TC does come on from time to time but I haven't had any problems getting stuck the last 2 winters.

Also, square track tires definitely does cause issues with TC but it does also depend on the track. At my local track (CTMP/Mosport) I ran into a ton of problems with Sport/Sport+/MDM, with no ability to put power down but when I went to Calabogie up near Ottawa it was nowhere near as bad. Another member here also found the same issues. I have since coded Euro MDM mode and that has resolved much of the TC involvement at the track.

I believe most track users with square set ups are running DSC Off so they don't have TC intervening at all.

I think I remember hearing about some dealers recommending a 235/255 stagger but on a square wheel setup or something, I suppose it probably is to keep a similar ratio front/rear. I'm starting my 3rd winter now on Michelin XIce 3 245/40R18 on 18x8.5 and I've had no issues getting stuck.

[bentom2]

I ran 245/40r18 square last winter and just mounted them up again. No issues with several thousand miles.

I also run 265/35r18 square on the track. Normally, I swap from the staggered OE wheels and tires to the track setup at home prior to the track event, but one time for a track that was farther away, I carried the track wheels/tires and switched at the track. I ran DSC on that day as I don’t know the track we’ll, and the traction control was very unhappy. Wasted my first couple sessions in the morning, but after that it was fine.

I always reset TPMS and put some miles on since for either setup when switching from OE. First couple miles if I get on the gas, the car freaks out, but then a few minutes later, everything seems to be recalibrated. The experience is similar to what you described, but at 40mph on my local streets.

Other than that one instance at the track no issues on track or the street. Maybe give it some miles to adjust and see what happens.

Worst case, weather isn’t too bad yet. Maybe swap the summer wheels back on and see if the issue persists? Inconvenient, but should allow them to focus on the actual issue. They certainly can’t blame the OE wheels and tires.

[mr_lab_rat]

Update (literally): I had the software updated from ancient 505 to 530 yeasterday. It seem to be much better, the MDM mode allowed me to slide the car way more than ever before.

It's too early to tell whether the issue is completely resolved but it looks promising.

[bri1042]

Like several others, I picked up the 641M set (19x8.5f - 19x9r - tires are 235/35's all around) from my local dealer (I was expecting to order them for cheaper but the parts gent gave me a good deal locally). I ran them last winter and the car was more squirrelly around curves than I'd want it to be. From what I can see, the Michelin Alpin's don't come in 255's. The M4 sets are Continental 255's on the same wheels.

I just put my 641's back on this last Sunday. I'll give them a second eval over the next few weeks to see if I'm OK with the handling or not. They were brilliant this morning in the pouring rain and cold roads.

[mr_lab_rat]

UPDATE: OMG, this is incredible. I'm loving the MDM in the new software. The problem with acceleration is gone and the car is way more fun now.