Vehicle Handling Issue

[HEEP]

Ok, so I know this is not a Mercedes forum, but I figured someone here might be able to help me.

So the issue is on my wifes ML350 Mercedes. She ran over something back in July timeframe, and had a tire go flat. I replaced both the rear tires, and left the originals on the front. This was at about 36000 miles and we are now at 40000. We drove it out of town this weekend, and it is squirrly. When you change lanes it seems to throw you into that lane when it hits line. If you hit a solid line, it pulls you to that side, it doesn't matter which side.

I was thinking I had too much air pressure and maybe riding on the crown, but when checking the monitoring system, it shows them to be right on in the rear and 2lbs low in the front. There were a couple of times, it pulled pretty hard. I don't feel anything in the steering wheel to show something might be loose, tires on the front have just hit the wear indicators and will be replaced soon.

Size is 255/55R19 and based onhe vehicle should be 44psi rear and 41psi front, unless loaded, which brings it to 48psi all the way around.

Any help would be greatly appreciated.

Bill