New Tire Issues - Traction Control

[Gizzard]

Hi all, long time lurker here, now in need of some help.

I just replaced the rear tires on my US 2003 C4S. They were previously Michelin Pilot Sports. I replaced them with Pilot Sport 2's, exactly the same dimensions etc.

Since replacing them, my Traction Control has been kicking in on one particular corner on my route to work. I am very familiar with this route, always used to take this specific corner at 70, never had the traction kick on. Now even at about 60, the traction kicks on.

Obviously this is causing me a little concern, and a bit less trust in the car. I went back to the garage that changed the wheels, they are a good outfit who I trust, they could find nothing obviously wrong.

So I wonder if anyone here has some insight?. Some extra info to clarify, I only changed the rears the fronts are still the PS1's, I have put about 500 miles on the tires since changing them, so its unlikley to be new tire wear in issues.

The tire shop did suggest that it could be the fact that I didn't change the fronts, but didnt know for sure. Does anyone have experience of this causing such an issue?

Could this be an alignment issue?

I would appreciate some thoughts.

Thx

[LVDell]

It sounds like a typical problem with tires when they are new. The tire will be very "greasy" for couple months. Should be fine shortly.

[djantlive]

I assume tire pressure is checked right? New tires have deeper tread and thus more flexible and not corner as flat. Is PS2 supposed to be harder than PS1? If so, that's probly your cause (harder rubber usually means less traction). Stiffness of sidewall also has similar effect.

[wwest]

The signals from the ABS front wheel speed, rotational rate, sensors are not comparing "correctly" with the rear sensors due to the "new" difference in overall circumferance of the rear tires.

Unplug the battery for 15 or 20 minutes but be sure you know the radio security code first.

[Gizzard]

It sounds like a typical problem with tires when they are new.  The tire will be very "greasy" for couple months.  Should be fine shortly.

<{POST_SNAPBACK}>

I assumed that this greasiness was connected to wear. Hence having done 500 miles on them it was unlikely to be a factor?

[Gizzard]

I assume tire pressure is checked right? New tires have deeper tread and thus more flexible and not corner as flat. Is PS2 supposed to be harder than PS1? If so, that's probly your cause (harder rubber usually means less traction). Stiffness of sidewall also has similar effect.

<{POST_SNAPBACK}>

The tire pressure is at 42psi, I changed it down from 44 to see if that helped but it made no appreciable difference.

Both tires are N-Rated which is as per the reqs for Porsche wheels as far as I know. I dont really know much about the hardness of the rubber. Just that Pilot Sports in general are not regarded as being very hard, hence they wear out pretty quick.

[JimPDX]

Hi all, long time lurker here, now in need of some help.

I just replaced the rear tires on my US 2003 C4S. They were previously Michelin Pilot Sports. I replaced them with Pilot Sport 2's, exactly the same dimensions etc.

Since replacing them, my Traction Control has been kicking in on one particular corner on my route to work. I am very familiar with this route, always used to take this specific corner at 70, never had the traction kick on.  Now even at about 60, the traction kicks on.

Obviously this is causing me a little concern, and a bit less trust in the car. I went back to the garage that changed the wheels, they are a good outfit who I trust, they could find nothing obviously wrong.

So I wonder if anyone here has some insight?. Some extra info to clarify, I only changed the rears the fronts are still the PS1's, I have put about 500 miles on the tires since changing them, so its unlikley to be new tire wear in issues.

The tire shop did suggest that it could be the fact that I didn't change the fronts, but didnt know for sure. Does anyone have experience of this causing such an issue?

Could this be an alignment issue?

I would appreciate some thoughts.

Thx

<{POST_SNAPBACK}>

[JimPDX]

I wouldn't do anything just yet. I don't think it has anything to do with tire mismatch.

I'd put about 300-400 miles on the tire and see if the brake in period stablizes the road grip. If it doesn't it might be that this specific tire can't handle the particular performance characteristics of your car esp. in the turn that you mention.

I think that is one reason why Porsche specifically recommends specific types, makes and designations, i.e., N2, N3, N4 and so on. Such designations indicate, among, other things that the tire can support the car as designed.

Edited June 13, 2005 by JimPDX

[1999Porsche911]

Since you have already switched tires once and the problem remains, you would have to assume that the problem is not with the tires. I would take the suggestion above and reset the computer by disconnecting the battery for a few minutes. If that does not work, you may have a sensor problem.

[plima]

Here are a few thoughts which might help you. I have a lot of experience with the Pilot Sport and now also with the PS2. Both are good sticky street tires, with the PS2 having the edge in that department. Thus I would not expect the problem to persist once the PS2 is "broken in." Typically, I would expect the new tires to be in pretty good shape within 500 or so miles. My experience with 911s, though, is that they are happiest with the same kind of tire on both ends. I can't tell whether you have PS2s with "N" rating or not. The "N" represents a Porsche-Michelin effort at good compatibility. In any case, give them a few more "aggressive" miles and I suspect you'll be fine.

[Gizzard]

Here are a few thoughts which might help you.  I have a lot of experience with the Pilot Sport and now also with the PS2.  Both are good sticky street tires, with the PS2 having the edge in that department.  Thus I would not expect the problem to persist once the PS2 is "broken in."  Typically, I would expect the new tires to be in pretty good shape within 500 or so miles.  My experience with 911s, though, is that they are happiest with the same kind of tire on both ends.  I can't tell whether you have PS2s with "N" rating or not.  The "N" represents a Porsche-Michelin effort at good compatibility. In any case, give them a few more "aggressive" miles and I suspect you'll be fine.

<{POST_SNAPBACK}>

Yep, they are the N-Rated ones. N2 in fact, though I only knew to look for an N rating.

[wwest]

Okay, look at it this way.

lots of new cars have low tire pressure warning indications.

Most of these work by comparing the rate of rotation of each wheel, using the ABS sensor signals, against a KNOWN, previously estabished, reference.

What reference?

Well, if you happen to RESET one of these low pressure warning systems while the tire in question is still low then a NEW (incorrect, but...) reference is established and the warning system will be perfectly "happy" unless it detects an additional change, relatively, in a tire's rational rate.

I know, personally, of instances wherein someone noticed a slightly low tire, re-inflated it to spec, and the low pressure warning light illuminated as soon as the car was driven. The newly inflated tire's rotational rate no longer matched the previously established reference for that tire in relation to the other three.

Disconnect the battery and be done with it!

Edited June 14, 2005 by wwest

[Gizzard]

Okay, look at it this way.

lots of new cars have low tire pressure warning indications.

Most of these work by comparing the rate of rotation of each wheel, using the ABS sensor signals, against a KNOWN, previously estabished, reference.

What reference?

Well, if you happen to RESET one of these low pressure warning systems while the tire in question is still low then a NEW (incorrect, but...) reference is established and the warning system will be perfectly "happy" unless it detects an additional change, relatively, in a tire's rational rate.

I know, personally, of instances wherein someone noticed a slightly low tire, re-inflated it to spec, and the low pressure warning light illuminated as soon as the car was driven. The newly inflated tire's rotational rate no longer matched the previously established reference for that tire in relation to the other three.

Disconnect the battery and be done with it!

<{POST_SNAPBACK}>

This does seem like its probably the best suggestion. I will give it a try this evening. Thx

[plima]

Please let us know it this resolves the problem; it will be a great education for us all!

[johnnys]

I have a 2002 c4 and have always had this proplem with pilot sports(both the ps2 and the older one's. Only when I got them really hot did the taction control stop going on In the worst places i.e very gentle turns at high speed I would go over a slight bump and the tc would come on and I would be thrown off line. Its actually very dangerous.. Even thought people say they are soft (the tyre wear is 220) they are a lot harder than pirelli's (even thought the new pirelli N4's also have a wear indicator of 220 they last half as long). You wont get ride of the problem unless you switch to pirelli's which are the only tyre to have on a c4 or c4s if you drive very hard. The Michelin are a good long wearing tyre for just driving around but not for serious c4'ing.

[C4S Surgeon]

The problem could be in mixing ps1's and 2's fr/r. I never mix tire brands or types.

I run Pirelli's as well, switched many a rear set, zero problems with the psm.

[1999Porsche911]

Ahhh...it's so nice having a car that will let you slip and slide when you want and not have some computer telling you where the limit is or to simply malfunction.

[wwest]

Hmmmm...

My Michelin pilots did an outstanding job on the track at Daytona just before the 24 hour race. PSM/TRAC never kicked in even once.

But then I try to drive the same way I fly, with my eyes and thoughts out in front, way in front.

[johnnys]

On the track the Michelins are fine with me too as I get them hot. It was just to keep them at the temp they like in stop start town etc driving was not safe.

As for mixing the brands there has been lots of discussion on that in the forum. I have said plenty so do a seach o that topic. I can say switching or mixing will definetly not be the proplem. The only thing apart from what I have already said is your tread depth. I always carry a small tread depth indicator (most typre shops willl give you one). If the difference bewteen your new tyres and old ones is to great i.e you fronts are 2mm and you rears are 7mm you may experiance what you are discribing check it out,

[Gizzard]

Okay, look at it this way.

lots of new cars have low tire pressure warning indications.

Most of these work by comparing the rate of rotation of each wheel, using the ABS sensor signals, against a KNOWN, previously estabished, reference.

What reference?

Well, if you happen to RESET one of these low pressure warning systems while the tire in question is still low then a NEW (incorrect, but...) reference is established and the warning system will be perfectly "happy" unless it detects an additional change, relatively, in a tire's rational rate.

I know, personally, of instances wherein someone noticed a slightly low tire, re-inflated it to spec, and the low pressure warning light illuminated as soon as the car was driven. The newly inflated tire's rotational rate no longer matched the previously established reference for that tire in relation to the other three.

Disconnect the battery and be done with it!

<{POST_SNAPBACK}>

This does seem like its probably the best suggestion. I will give it a try this evening. Thx

<{POST_SNAPBACK}>

So I did the battery thing. It made no difference. I guess I am not really surprised, it seemed a little unlikely that the system worked this way, I would expect that it would average itself out over time.

So I am a bit at a loss as to what to do next. I am not much enjoying of the TC coming on in places I know very well it doesnt need to. I also dont really want to go fork out another $1k on a complete new set of tires if I can avoid it.

I did check the tire depths, just to make sure. I have about 5mm on the fornts and 7 or so on the backs. So thats probably not it either.

Edited June 18, 2005 by Gizzard

[johnnys]

Which tyre's is losting traction do you know ? is the fronts or the rears ?

Also If you found my posting on tyre mixing what I did when this happend to me was to run pirrelli up front and the ps2 at the rear. This was a fantastic combination as the tyres wore at the same rate. I got 25,000km from the pirelli up front and 20K Km from the Michelin's at the rear. I have since changed to pirelli N4 which actually take the cars handling to another level.

Do you have a friend who has a 996 and try swapping tyres. Even though it is the rears you replaced try swaping the fronts and you'll be pleasently surprised.

If you do decide to spend some money do it progressively I.E by some pirelli's for the front first then have a drive. If that fixes the problem stay with it I drove mine with that compination for 2 years. No one including porsche could give me a reason why this would not be ok as both the tyres are n rated. Then if that doesnt work (im sure it will) then go to pirelli at the rear and keep your michelin's for the track. or sell them on the internet. or your tyre shop my buy them back. they are still worth a lot of money.

Of course disconnecting the battery would not work. These are modern cars.