Need Help with handling issue with new tires...

I got 2015 GT PP with 15K miles on it. I just replaced the Rear P-Zero's (summer only) with Conti Extreme Contact DSW06 (all season). I only replaced the rear because the front still look new. I did a lot of research and seen no bad reviews for the Conti, and did find a lot of good reviews. Even on this site.
So here is my issue... After replacing the tires my car handles differently, not in a good way. I notice it more at higher speeds and at higher revs. It twists under load. So when I am doing about 80mph in 5th (manual) if I accelerate quickly I feel the ass end dip to the left and the front pull to the right. and when I quickly stop accelerating such as when I am shifting it dips back or straightens out quickly. It's not just a little movement it's VERY noticeable.
I also feel it being a little squirrely in the ass end when I'm switching lanes, like where the road has dips in it. I didn't feel this when I had the P-Zeros on.
I didn't change anything else but the rear tires and the Lugs are tight.
I looked at the tires to see if they are directional and I do not see any markings on the tires indicating that they are directional so I dont think they are on backwards, but I could be wrong.
Has anyone ever experienced this before?

Either the alignment is out or the tires have radial pull.
Try switch left and right see if it helps.

jasonstang said:

Either the alignment is out or the tires have radial pull.
Try switch left and right see if it helps.

Click to expand...

I will try switching the tires. and see what happens

The Alignment was just done on the car less than 2 months ago when I put on the lowering springs

You're not supposed to mismatch tires...

CommyO said:

You're not supposed to mismatch tires...

Click to expand...

Ya...I knew someone would mention this....but that would have nothing to do with what I'm experiencing.
Perhaps if the left rear was different than the right rear then maybe that would be the issue.

People always say that and I remember when every muscle car had different tires on the back than on the front.

psoff said:

Ya...I knew someone would mention this....but that would have nothing to do with what I'm experiencing.
Perhaps if the left rear was different than the right rear then maybe that would be the issue.

Click to expand...

It is the tires. Put the stock ones back on and see what happens. It could be the difference in grip and tread pattern

I bought my 15 GT in the middle of Aug. last year. I switched to DWS06's in 275/35/20 due to the cold temps here in Reno. I just switched back to the factory P-Zero's since they only had 1200 miles on them so I could save the more expensive all seasons. I ABSOLUTELY HATE THE WAY THE CAR DRIVES NOW!!!! My car handles much better and tracked much better than it does now. I had to take a trip to CA last week, and my car was pulling and swaying all over the place (really shitty road surface from tire chains chewing up the lanes). I made this same trip 3 weeks earlier with the DWS's and didn't have this issue at all. I'm really thinking about blowing these tires off with a butt load of line lock runs and putting the DWS's back on. I'm thinking your issue is either mismatch of tires or they didn't mount the tires in the correct directional pattern. I couldn't be happier with the DWS's than I am and will never go back to the POS-Zero's.

To me it seems to be the tires.

Continental DWS have a much softer sidewall then the P-Zero summer tire so it could feel different/lazy compared to Pirelli.

I just put new wheels and tires on (staggered) 19x9 front 19x10 back nitto invos front 255/45/19 back 285/35/19's and the car is more stable handles better now...never liked pirelli tires!

CommyO said:

It is the tires. Put the stock ones back on and see what happens. It could be the difference in grip and tread pattern

Click to expand...

I cant put the stock ones back on. I replaced them with the DWS's because they were bald.
I will be going back to the tire shop tomorrow and see what they will do for me.
This is seriously more than just a little bit of movement. and when I shift gears in a curve I almost lose control of the damn car.
I believe there is something seriously wrong with the tires. Like a manufacture defect.

I replaced my p-zeros with the dws06s about 7 months ago. I've been happy with the tires, and the durability has been phenomenal. Lost a touch of steering response but the rear grips much better.

This said, I had mixed feelings initially. Like someone above said, the sidewalls are significantly softer than the pzeros. When they were put on they were set to the cars recommended psi, which made the car ride very smooth, but after experimenting I found it was simply too low for the tires. The handling felt floaty compared to the pzeros and the tread was wearing too far out on the edges.

I set the fronts up to 38psi cold and the rear to 37psi cold and it made a huge difference. The front end was immediately more responsive, the car felt more composed, I didn't lose any ultimate grip, and it corrected the treads contact patch.

psoff said:

I will try switching the tires. and see what happens

The Alignment was just done on the car less than 2 months ago when I put on the lowering springs

Click to expand...

Hey psoff, I noticed that floaty feeling occasionally after lowering my car. If you have not clocked the suspension after lowering the car, you may want to give it a try before dumping those good tires. Cleared my issue. If your lucky like I was, you wont need to do another alignment. Hope you get sorted out

http://www.mustang6g.com/forums/showthread.php?t=44129

The difference between all-seasons and summer tires. Sidewall flex, grip, handling.

Did you replace with the same exact size tire?

You didn't expect an all season to handle turns the same as a dedicated summer tire, right?