dc7391

I had some new rear tires mounted the other day on my 2017 TTS. Now when i take an on/off ramp at normal or slower than normal speeds, sometimes the traction control light comes on. Where is this sensor located? Is this something that could have been triggered from the tire swap? I went with the same brand and size as before. Here is a clip. Sorry in advance for the poor recording. You can clearly see the speed and angle of the wheel. Suggestions?

Jim M.

Do you have Porsche adaptive-cruise-control-with-porsche-active-safe-pas? If so I believe it is telling you that you are to close to the car in front of you. The symbol is very similar, the difference is the arrows under the symbol.

dc7391

I do not no. It comes on even if there is no one in front of me.

MaxLTV

Are rear tires the same diameter as the ones you replaced? This often happens when tire diameter is changes, even if it's slightly different. Sometimes even happens when changing to new tires from old tires of the same size, just because the difference in wear can result in difference in diameter sufficient to trigger this effect.

dc7391

Nope, same brand and size as before. But even if i did change the size, is there a way to do a reset/learn?

MaxLTV

In my experience, it calibrates automatically after driving straight for few dozen miles.

dc7391

Not the case here. Have about 50 - 60 miles on these new tires.

MaxLTV

It's very unlikely that ABS sensor or any other sensor was affected during a tire change - it's not exposed. I'd check pressures to make sure they are sharp on spec and keep driving for a few more days. I often change tires on just one axle, and sometimes I get the same effect, which goes away after driving for a little while, like an hour on the highway is usually enough.

dc7391

Thank you for your help, ill try this.

kitwetzler

Make absolutely sure they put the right size on the car. 305/30r20. I've seen tire shops make small mistakes that turn into large ones... The Porsche AWD system is very sensitive to tire diameter.

M3S3R

Dealership should be able to help you out no charge. Car is still under warranty. Interested in the out come as I'm getting ready for new tires. How many miles did you get out of your last set of tires?

Need4S

New tires? Most likely the mold release compound (very slippery stuff) is still on them. Drive for 100-200 miles and it should wear off or go away. It will dissipate faster if you drive it in the rain. It's water soluble so you can also try washing it off.

dc7391

So after much research and measuring it seems that by only changing the rear tires and being that the fronts are down to the bar, its the difference in overall diameter that is triggering the traction control light. I have the new fronts on order and should be installed this week. Fingers crossed this solves the issues. MAN these cars are sensitive.

Jean

MaxLTV

Exactly. I've run entirely different size in the back (295 instead of 305) and the car would flash traction control and cut power at first but it went away after an hour on the highway. I'm surprised it's not going away. When you install winter tires, for example, the proportion is not exactly the same as for summer tires, but the car adapts.