Hi Guys,
My car is '11 GT that came with the Brembo package, stock 9x19 wheels, Pirellis 255/40R19. I lower it with STEEDA Sport springs and felt great, then I replaced my rear tires with Michelin Super Sport 275/40R19 car felt great with a strong grip. Then later I replaced my fronts to that same size, immediately I noticed a faster steering that felt great, but now after a long drive at speeds of 80-90 mph the car felt unsafe if for any reason I moved a litle bit my hands on the steering immediately the car will try to change lane, I had to be very concentrated on my driving, I kept the stock 35 psi. Please advice.

 

Sounds like you need an alignment change, maybe a little more toe in.

At the very least have the alignment checked by a good shop.

 

Is your steering response set on the 'comfort' setting? On the highway I set mine on 'sport' to give a bit more resistance to the feel.

 

On the '11 I don't have that steering adjustment settings but it should be an alignment issue.

 

If you have a Firestone local, they have lifetime alignments. It costs twice as much but you can go as often as you need. If you have it aligned 3 times, you are ahead.

 

Lifetime alignments huh? That sounds intriguing.

Agree with above. It's not the tires, plenty of people run a square setup wider than stock. Get an alignment and you'll be good

 

Couldn't a square setup cause the steering response to be stronger in the front?

 

I have a lifetime alignment on my 2007 Jeep Liberty. It has a 3 inch lift on it and the new manager at the closest Firestone was not happy to be doing a "free" alignment for me. He said they normally charge extra for lifted. Not sure if he would say same on a lowered car or not. I'll probably go to another Firestone when it's time for the Mustang. I've had my Jeep aligned at least twice a year for the past 3 years .

 

Some firestones have the equipment that does NOT leave divots in your rims/wheels and some do have the proper equipment. My car is lowered and uses camber bolts. You have to let them know you have camber bolts or they won't even mess with the camber setting. Also one of the firestones told me they could not do the alignment with my 20 inch rims. I have a life time with firestone but ended up going to NTB for my last alignment because of my 20's


I would think/hope the steering would be more sensitive with wider tires up front. But you are saying its to sensitive?

 

Lowered PSI, problem solved

 

What were you running them at?

 

I had this same issue after new tires, an alignment fixed this.

 

35 psi all four like stock. I lower it, fronts to 32psi & rears at 31psi. My GT felt much better, like it was before (not nervous on front).
I'm planing this weekend to leave the fronts at 33psi & rears at 29 psi, this psi setup apparently will improve the handling of my new tires.

 

Are you sure you don't have the steering options? I thought that came in 2011 with the new engines and EPAS....

 

That was a '12 upgrade