Continental buyers, Beware!

[7Andrei7]

Hi guys!
Last winter I went through some serious trouble with my Stinger. My TC was inexplicably cutting power during hard acceleration, especially at high speed. I got to the root of the problem. It was my set of staggered Continental TS860S that had a massive circumference difference between front and rear. The car was registering a speed difference between the front and rear wheels of up to 4-5 km/h under acceleration and cutting power. The moment I switched to my other set of tires (summer, same sizes) the problems disappeared.
More info towards the end of these threads:

LSD = More traction control?

You can use tape or a paint pen to mark them at the same location (edge of tread or sidewall for easier viewing), do a full rotation of each, and see how far ahead/behind the bigger/smaller one is. It'll be about 3x what you're seeing in height, and without the potential parallax error.

stingerforum.org

2019 Kia stinger GTS losing power on the freeway after reaching a certain speed

For what it's worth, it's UNLIKELY that it's 2 wheel sensors... If you have access to an oscilloscope and a multimeter, you can test the sensor, see the last page here. I also think it's unlikely for both sensors to randomly start reading a 1-2% higher speed. They don't have weird oscillations...

stingerforum.org

The decision from Continental was to replace my tires with a new set. I didn't think to measure them because I assumed the old set was an anomaly. Well, guess what. The new one is exactly the same. The rear tires appear to be smaller than the normal spec.

I reached out to Continental and asked them what were the official results of the tests they did on the initial set. They refused to disclose the information. They claim this is "not publicly available information". This is despite the fact that I am the one who made the claim.

In any case, they asked me to send back the new set as well. I hope they will give me my money back, BUT, anyone thinking to buy these tires will get the same as me. I'm now 100% sure that they have a production issue and ALL their TS860S tires in 255/35R19 are smaller than they should.

FYI, fronts should be 2080mm. They are 2083mm.
Rears should be 2075mm. They are 2057mm. Brand new.
Combining them gives a 1%+ difference in diameter which will screw up both TC and potentially the Transfer Case.

 

[44pirate]

Basterds.

 

[oddball]

What's the continental tech sheet say for those? Most brands will advertise the "rolling diameter" of each size of a particular style of tire.
The size markings (225/40R19) are a general classification. There is a TON of variation within each of those size markings. The sidewall ratio is to the nearest 5%, tread width is to the nearest 5mm, and "tread width" is an extremely subjective term. About the only thing that isn't bonkers is the rim diameter.

Always have to check the tire manufacturer spec sheet when mixing sizes on AWD cars. No if's and's or but's.

 

[7Andrei7]

@oddball yeah, they also refuse to disclose that information. I could not find it anywhere.

 

[TerdBath]

Interesting that it only takes a 1% difference in tire circumference to cause the issue.

 

[ElChanclo]

FYI, fronts should be 2080mm. They are 2083mm.
Rears should be 2075mm. They are 2057mm. Brand new.
Combining them gives a 1%+ difference in diameter which will screw up both TC and potentially the Transfer Case.

View attachment 87460View attachment 87461View attachment 87462

Were these photos measured while inflated or deflated?

 

[oddball]

Were these photos measured while inflated or deflated?

Even that doesn't matter. The tire will distort, so the effective rolling diameter is what really matters. That's not even easily figured from the height of the tire when it's on the car!

@oddball yeah, they also refuse to disclose that information. I could not find it anywhere.

Yeah, I spent 5 minutes looking for it, and appears they don't easily publish a tech sheet. I haven't checked every tire manufacturer, but I've never had a problem getting a tech sheet before..... Even Tire Rack only has rolling diameter for a few random sizes.

 

[7Andrei7]

Were these photos measured while inflated or deflated?

These measurements are with the tires deflated. When installed on the OEM wheels, the difference between front and rear actually increases by about 10mm (to 35mm). Even worse.

What I can tell you is that my summer set of Goodyear F1 Asym6 is within the required 5mm difference (front-rear). Same with the previous Michelin PS4. It's only the Continental TS860S that has these wild 30mm+ differences between the front and rear tires.

Interesting that it only takes a 1% difference in tire circumference to cause the issue.

Yup, not a lot of tolerance. The thing is that when inflated the difference is slightly higher, about 1.5%. So this means that at 140 km/h (cruising speed) you will have a constant speed difference of about 2 km/h. If you floor it, with the winter tires being so soft, there is a moment when that difference will spike. If you're curious, take a look at the topics I linked above. I have it documented very well, including videos of live speed readings.

 

[ElChanclo]

These measurements are with the tires deflated. When installed on the OEM wheels, the difference between front and rear actually increases by about 10mm (to 35mm). Even worse.

I'm gonna start measuring circumference along with dread depth when changing wheels over now. You never know.

 

[Snicklefritz]

I'm gonna start measuring circumference along with dread depth when changing wheels over now. You never know.

Ima not going to do this measuring thing. The last thing I need is yet another aspect of the car to get all OC about.

I've read all of @7Andrei7 's threads on this fubar. What I don't understand is why he measured uninflated tires. But that's an aside.

The Stinger manual specifically says to replace tires with the same size as came on the car. Andrei did that with winter Continentals. But the difference starting out brand new was way more than the c. 2mm supposedly smaller in the rear. A calculator is only that. It isn't an exact measurement of the manufactured tires in question. And KIA cannot guarantee that in the future, the tires they supplied with the car will continue to be reliably manufactured to spec. While within warranty, since I have put the OEM tire sizes on, regardless of the manufacturer, I should be within warranty. KIA would not put these staggered tires on, with the rears wearing down twice as fast, if that would bring on AWD system stress/failure. The respective tread depths have to be within tolerances, or we would be warned of potential problems. But KIA has not, to my knowledge, ever put Contis on the Stinger? I wonder if KIA knows about winter Contis being so disparate front to rear with OEM tire sizes?

 

[ElChanclo]

Ima not going to do this measuring thing. The last thing I need is yet another aspect of the car to get all OC about.

I can respect that, but some of us like to have a bit of fun which involves going off-manual.
This requires some good old fashioned research, collecting data and information.

I only found out about the "AWD error" when test fitting some snow tires that were 1.7" taller than OEM, and I've been trying to find the systems limit before flagging the warning light since then.

So it's weird to me that @7Andrei7 was experiencing issues but not triggering any warnings.
Would an OBD reader pick anything up?

I had a 0.9" diameter delta without triggering a fault, but it was only a short drive through the neighborhood. Either way I concluded the strain on the system is exponential with larger wheel deltas so the less the better. No 2 tires are the same really so there's some room for error.

 

[Kodiack]

A normal OBD2 reader would only give you a TC code, a diagnostic tool would tell you the live data of the wheel speed sensors while driving.
Mine would alert the out of range sensors and they show up red. It would probably throw a code for each not sure, I have never had that issue.

 

[socalvn]

My Continentals are driving just fine
Plan on repurchasing the same Tire when the time arrives

 

[Ozstung]

Ima not going to do this measuring thing. The last thing I need is yet another aspect of the car to get all OC about.

I've read all of @7Andrei7 's threads on this fubar. What I don't understand is why he measured uninflated tires. But that's an aside.

The Stinger manual specifically says to replace tires with the same size as came on the car. Andrei did that with winter Continentals. But the difference starting out brand new was way more than the c. 2mm supposedly smaller in the rear. A calculator is only that. It isn't an exact measurement of the manufactured tires in question. And KIA cannot guarantee that in the future, the tires they supplied with the car will continue to be reliably manufactured to spec. While within warranty, since I have put the OEM tire sizes on, regardless of the manufacturer, I should be within warranty. KIA would not put these staggered tires on, with the rears wearing down twice as fast, if that would bring on AWD system stress/failure. The respective tread depths have to be within tolerances, or we would be warned of potential problems. But KIA has not, to my knowledge, ever put Contis on the Stinger? I wonder if KIA knows about winter Contis being so disparate front to rear with OEM tire sizes?

Just to your last part about Kia not to your knowledge used Continental tyres.

Kia launched the Stinger with the Continental Conti contact 5 for two seasons MY2018 & MY2019. I'm not sure if that was globally but it was in Australia.

 

[Snicklefritz]

Just to your last part about Kia not to your knowledge used Continental tyres.

Kia launched the Stinger with the Continental Conti contact 5 for two seasons MY2018 & MY2019. I'm not sure if that was globally but it was in Australia.

Could this OD difference due to a manufacturing fubar possibly be the reason that KIA moved away from Contis?

 

[Ozstung]

Could this OD difference due to a manufacturing fubar possibly be the reason that KIA moved away from Contis?

No, as i remember they preferred the PS4 then PS4S because it was deemed a better tyre. But who knows what goes on behind the scenes.

I heard nothing about diameter issues at the time.

 

[7Andrei7]

I've read all of @7Andrei7 's threads on this fubar. What I don't understand is why he measured uninflated tires. But that's an aside.

The only reason I measured them uninflated as well was to compare to the standard circumference for those specs, which is calculated uninflated. Here are the inflated measurements on the same brand new tires. They are on the 19" OEM wheels my Stinger came with. Fronts are 2115mm and rears are 2080mm. That's a 35mm or 1.7% difference. The 1.7% difference is also valid for overall diameter. This is massive and in line with the speed readings below.





@ElChanclo I did not get any errors because my car is RWD. The only thing it did was trigger the TC (only in comfort/eco modes) when fully accelerating at high speed. In a straight line, even on dry asphalt. For example, when trying to overtake.
Readings with a professional diagnostic tool show a spike in wheel speed differences front-rear. Here are 2 readings, at cruising speed (2km/h difference) and under hard acceleration. The second is when the TC would cut power.




@Ozstung my Stinger also came with summer Continentals and I had no issues with those. I think it's just about the TS860S model. Which is the only Winter UHP Conti makes in the Stinger sizes.

 

[Ah GetFd]

Maybe the plan should be to upgrade to the Michelin Sport that were delivered on the My 23 Stingers from the factory.

 

[Snicklefritz]

The only reason I measured them uninflated as well was to compare to the standard circumference for those specs, which is calculated uninflated.

See, I didn't know that. Thanks for educating me.

 

[7Andrei7]

Ok, so basically Continental told me go f myself. And they blamed Kia for not requesting a special set of staggered tyres like Merc or Bmw do.
They claim that tires can have a massive tolerance in rolling circumference and it's all within spec. It's Kia's fault for mixing the 2 different sizes if they knew this kind of difference could trigger the TC.

The tolerance can be between -2.5% and +1%. It happens extremely rarely but they are covered when it happens.
Yup, bye-bye transfer case.
And bye-bye Continental, for life.

If you insist on buying Continental, get the MO marked ones. They are made for Mercedes and those specific sizes are required to be within a special tolerance between front and rear sizes.

Extract below from the document they gave me to justify not accepting the return.