[haru69]

Hey everyone,

I've got a BMW G26, and after putting on Continental Sport Contact 7 tires, I'm getting an odd issue. When I hit around 150 km/h and give it about 50% throttle, the traction control light flashes and the engine power cuts out. It doesn't happen every time, but I'm thinking it might be tire-related. Any ideas what's going on?

new tires are the exact same spec of the previus tires i had
i already have put my old tires and there is no issues

this is the response from continental (outrageous):

Good morning.

We have examined the information provided and can confirm that the reported phenomenon is not attributable to manufacturing defects of the tires, but rather to incorrect equipment.

Since this is a BMW Xdrive vehicle with different sizes between the two axles, it is practically mandatory to install BMW-approved tires, i.e. "starred" tires, as recommended by BMW itself.

These tires have lower manufacturing tolerances than the ETRTO standard ones, to adapt to the characteristics of the Xdrive transmission, which in turn has limited tolerances.

Installing non-approved tires can lead to malfunctions of the vehicle's traction/stability control systems and, potentially, damage the mechanical parts of the transmission.

We attach a technical sheet that deals with the topic and we recommend that you only install BMW-approved tires on the vehicle.

[pbonsalb]

Brand new tires still have the release agent from the mould that reduces traction for maybe 100 miles. If you have driven more than that I have no idea unless you also changed tire sizes.

[Hit_Apex]

Assuming you chose OEM sizes you might need to reset TPMS. Manually check/adjust pressures before doing the reset. Other possibility is tire diameter mismatch - xDrive requires diameter to be within 1% front to rear and will cause error codes driving at high speeds.

[haru69]

Originally Posted by pbonsalb

Brand new tires still have the release agent from the mould that reduces traction for maybe 100 miles. If you have driven more than that I have no idea unless you also changed tire sizes.

I have driven already 500km and they still have this issue
Today I have put my old tires and there is no traction control issue anymore
So I guess these tires have some type of defect ?

[haru69]

Originally Posted by Hit_Apex

Assuming you chose OEM sizes you might need to reset TPMS. Manually check/adjust pressures before doing the reset. Other possibility is tire diameter mismatch - xDrive requires diameter to be within 1% front to rear and will cause error codes driving at high speeds.

Yes the tires are OEM size
The pressure is perfect
I went to both the BMW dealership and where I bought these tires. Both told me one tire has a slightly different diameter, which is why the traction control senses one tire slipping more than the other and cuts power while accelerating

[Redd]

What tires did you have before?

[tracer bullet]

Originally Posted by haru69

I went to both the BMW dealership and where I bought these tires. Both told me one tire has a slightly different diameter, which is why the traction control senses one tire slipping more than the other and cuts power while accelerating

Tell them to fix it

[haru69]

Originally Posted by Redd

What tires did you have before?

Hankook

[haru69]

Originally Posted by tracer bullet

Tell them to fix it

The Place where I bought the tires have sent a complaint to continental

[NSXR]

Yay for giving the car 50% throttle at 90 mph.

Surprising issue from a Conti SC7.

[DubaiRich]

I'm running the same tires and no issues...thus far

[haru69]

Originally Posted by NSXR

Yay for giving the car 50% throttle at 90 mph.

Surprising issue from a Conti SC7.

yeah well not even a 800hp car can spin wheels at 90mph
mine just has 300hp..
pretty sure is a tire related issue

[DomMuc]

sounds like wrong spec tires ...
are tires ( Size / height/speedindex/weightindex) exactly on the Airpressuresheet in your Diverdoorwell?

[haru69]

Originally Posted by DomMuc

sounds like wrong spec tires ...
are tires ( Size / height/speedindex/weightindex) exactly on the Airpressuresheet in your Diverdoorwell?

the size are the exact same
245 40 19 98y
255 40 19 100y

[DomMuc]

usually you need 245/35 and 255/35 R19 and not 40 40 is mostly on 18" rims

[haru69]

Originally Posted by DomMuc

usually you need 245/35 and 255/35 R19 and not 40 40 is mostly on 18" rims

on my g26 is 40
for the 18 rims is writen 45

[haru69]

Well I guess I will never buy continental anymore that's their response 😅

Good morning.

We have examined the information provided and can confirm that the reported phenomenon is not attributable to manufacturing defects of the tires, but rather to incorrect equipment.

Since this is a BMW Xdrive vehicle with different sizes between the two axles, it is practically mandatory to install BMW-approved tires, i.e. "starred" tires, as recommended by BMW itself.

These tires have lower manufacturing tolerances than the ETRTO standard ones, to adapt to the characteristics of the Xdrive transmission, which in turn has limited tolerances.

Installing non-approved tires can lead to malfunctions of the vehicle's traction/stability control systems and, potentially, damage the mechanical parts of the transmission.

We attach a technical sheet that deals with the topic and we recommend that you only install BMW-approved tires on the vehicle.

[pbonsalb]

I am running Conti EC Sport 02 on my 2018 M5. Not Star spec and no issues. In fact, BMW uses the same Conti tires on the M5s at its Performance Centers.

But yes, if the front to rear diameter difference is more than about 1%, there can be traction control issues. At 90, tires are hotter. Could be the rears are much hitter than the fronts. Heat causes expansion. Maybe there is some way to check this and maybe use inflation pressure to fine tune.

[haru69]

Originally Posted by pbonsalb

I am running Conti EC Sport 02 on my 2018 M5. Not Star spec and no issues. In fact, BMW uses the same Conti tires on the M5s at its Performance Centers.

But yes, if the front to rear diameter difference is more than about 1%, there can be traction control issues. At 90, tires are hotter. Could be the rears are much hitter than the fronts. Heat causes expansion. Maybe there is some way to check this and maybe use inflation pressure to fine tune.

my previus tires were exact same size..
i have heard from other people with my same car with these tires and they have no issues..

[pbonsalb]

Could there be a different issue than the tires? I know the timing makes the tire change the prime suspect. Any tuning or other work done at or around the same time? Damaged ABS sensor can operate intermittently, for example.

[haru69]

Originally Posted by pbonsalb

Could there be a different issue than the tires? I know the timing makes the tire change the prime suspect. Any tuning or other work done at or around the same time? Damaged ABS sensor can operate intermittently, for example.

i have put my old tires right now and everything is fine.. no more traction control issues

[Hit_Apex]

This whole story is weird. I'm having trouble believing one tire was made >1% larger than the other in the same labeled size. I'm not surprised by Conti's response to use star tires, but interesting that they claim tighter manufacturing tolerances - I've not heard that before. 'Kook FTW. Maybe try again with Michelin.