hockeychamp

Thought I'd see if someone can figure this one out. Current set up is 996 4S with Sumitomo HTRZ III tires. I changed the rears due to wear and since the change, every time I am on a freeway interchange on my commute banking left at 52-53 mph traction control comes on and my rear tires seem to flex too much and I slide a bit lateral then regain control. I checked the lug nuts. Tire pressures seem OK 36 from, 38 rears.

Is this a tire problem (treads too new)? balance? or should I have swapped out all four tires since its a 4S

Never had this problem with my old Sumis.

No HTwo O

Give it about 500 miles to scrub in the new rubber and burn off the mold release.

Ubermensch

Agreed. You always want to be careful on a new set of tires until you get them broken in.

S.

washington dc porsche

+1 on the grease.

TomF

New Sumi tires are slicker than snot before they are broken in. I have the Sumis as well and they are squirrely for the first couple of hundred, maybe more, and they are downright awful for the last 2k miles... For the money, they are a great tire, but you really only get to enjoy them for maybe about 80% of their life. They are noisy when new and at the end, BTW.

Dennis C

+1

SSST

Take it to a big empty parking lot, turn off PSM, crank the wheel all the way to the left, then dump the clutch at 5000 RPM.

That's a quick fix to the problem. Otherwise give it some more miles and you should be fine.

Pac996

Might want to watch out for rim slip also. My sportbike had an insane slip with fresh tires when braking heavy for a light. Tires when new can slip on the rim since the rims are smoother than the road and the shops normally add enough lube mounting. Break in is also good for letting the internal bands get settled with the new rubber. Turning from lock to lock with new tires when parked is a good way to find out that charicteristic of prebreak in of tires. The belts can shift and leave you with a thump when driving.

nick49

I had the exact same problem with my Turbo. This is when I put new Sumis on the rear with 50% Michelin PS2s on the front. The car rear would break loose and slide and PSM would intervene. I found this to be because the circumference deferential was too great between the F to R. I fit some new Sumi fronts and all is well. In fact pushing the car really hard on the street and in the canyons, the Sumis give more confidence and feel better than the PS2s. The Sumis will stick in the same turns that the PS2s would break loose in. This is comparing new Sumi HTR-Zll to 2-3 year old Michelin at 50% rear 70% front. I'm pretty sure on track the Sumis would get greasy feeling sooner and the Michelins would handle much better at elevated temperatures.

targa996

38 rear sounds like low pressure ... not sure whet c4 spec is but c2 is 44 ....

mjb2448

If this happened to me in my 4S I'd be squelling like Maxwell the Pig from the Geico commercials.

Edgy01

For 996 4s and Turbos having any sort of tire delta between from and rear will definitely impact the control electronics in the car and you will get yourself in trouble in no time. Get the new tires broken in but do nothing exotic until you do. This is a well know issue.

hockeychamp

Thanks for all the great replies. I guess I was lucky the first time I put the Sumis on and didn't have this experience / delta difference. What I sense when is exactly what Pac996 describes.

I'm going to listen to you all and really take my time while the tires get broken in.