I guess it's Porsche way of telling me to brake before the corner.

 

The only time my car has behaved that way was when I had an out-of-spec diameter tire in the rear, or if I noticeably mismatched wear/grippiness in front vs rear. I gather you do not have those situations in play here, but the symptom you described is exactly what happens when my car has either of those going on.

 

The car came with new Ventus tires in the rear and ? Original Bridgestone in the front. The front still had lots of tread. I wonder if that's what's going on.

 

can't say it that's the root cause, it could be, but having mismatched tires is really bad.

 

Mismatched tires is a big no no. Different compound, grip levels, sidewall stiffness...its a wonder you have not crashed yet. I have Ventus V12 all around on my 09 C4S, and they can squirm quite a bit, but all four do it at the same rate. The Bridgestone fronts will not work with the Ventus rears.

 

Old out of date concrete compound tires.
More that 3 ish years old? Get hard.
8-9 years old? Silly.
Santa delivers to your house this very month. Put four on your list.

 

Tire Santa!!

 

I mean the the front tires were oem Bridgestone not the original tires. The car has 43k miles and the tires has over 70% tread left. I doubt they are the original tires.

after thinking about it some more, I don't think it's the psm but rather the abs that's kicking in, or at least that's what it feels like.

Its just frustrating because I'm no where near the limit when it kicks in. Abs works fine in a straight line. The pulsitating pedal only happens when in a curve. Guess I need to take a trip to the dealer.

 

The PSM is essentially the ABS activating when things aren't smooth in the corner. The PSM system will actuate the ABS system on whatever wheel will correct the problem. If I were you I would just go get 4 new tires and be happy knowing you have new shoes that will last you a awhile without second guessing how old they are. Mis Matched tires on these cars is a bad idea as other have said. I'd be hesitant to turn the PSM off. If it's kicking in that means sometheing is wrong and by turning it off, you're eliminating a feature that could save you from getting out of control.

 

Ridiculous.

I have driven several cars with different brands of performance tires front/back, including my Porsche. When you drive a car that goes through rear tires at twice the rate as the fronts, it just happens.

If driving a Porsche with two different brands of tires puts someone in a ditch, that driver doesn't need to be in charge of anything more powerful than a Hoverround scooter.

 

if you are commuting or puttering around sure go ahead and mismatch brands. If you are driving aggressively or at the track, then not such a good idea. I have Ventus V12, they squirm....Bridgestones are stiffer, I've had them in the past. Squirm back and firm up front, not good and the ECU and ABS and TC is not programmed to handle that either. If he wadds it so be it.

 

Are you canyon carving? Are the roads highly trafficked? I found that So Cal roads get dusty/sandy quick if they haven't been trafficked much. So if you're hard braking through a corner on even a slightly dusty road, then yes PSM with activate ABS to add understeer and keep the rear from swapping ends.

You can drive a corvette like that but not a 911.

 

This has come up in the past and my advice has always been tempered with the caveat that if you're tracking the car, only mix brands if you know what you're doing and never mix brands side to side. But the fact is that most of these cars are being driven at a peak of maybe 7/10ths and most much less than that, which makes mixing brands a non-issue.

Also, the levels of grip at the front and back are always different anyway. You have over 2 inches more tread width on the ground in the back with the rears loaded much more than the fronts, different sidewall heights and you have to consider that the rears wear out twice as fast as the fronts, making the depth of tread different at all times. This makes the two ends of the car completely different, even with the same brand of tire at all four corners.

The traction control is programmed to react to wheelspin, yaw, and a bunch of other variables but it's not particularly smart. It just constantly runs through a series of "if x then y" situations. It is completely capable of accounting for the differences between two different brands of performance tire.

 

Mine does this too on cloverleafs, even if just lightly touching the brake pedal. Glad I'm not the only one.

P.S. I only drive in Sport mode, so not sure if it would occur in normal mode.

 

i happens in normal mode also. Doesn't happens when psm is disable.

In my case I don't think it has to do with the different tire brand front and rear. On those off ramps I'm going maybe 2/10. I've done canyon carving and psm hasn't kicked in. Then again I'm only going maybe 5/10. Lots of blind corners on the canyon with rocks in the middle of the road where I drive.