Need some help solving poor handling issues.

[Cleanest135i]

Hey guys so I am not sure exactly what is going on with my car and would really appreciate some help. So I have always felt a lot of side to side movement in the car especially when going over small bumps under power. But recently it became far more pronounced and now it almost feels like my tires are fighting with each other on where to make the car go if that makes any sense and I get lots of small steering wheel movement while going straight at highway speeds. I did 2 different things at the same time that maybe could be the cause? So the first is I stiffened up my front shocks because they were all the way on soft and very bouncy, so would I possibly need to stiffen up the rear to balance them out? Also the other thing I did is I got new tires on the rear of the car. I have PSS on the front with about 60% left but the rears were toast so I got some Kuhmo ps91's. Could the tread be messing with each other or something or do I need an alignment? I dunno these are my ideas but I'd love to hear yours and get this thing not feeling crazy sloppy at highway speeds.

[ASAP]

Almost all sloppinesz in this car is resolved by rear subframe bushings and good toe arms... trust me... btw the more traction your rear tires have, the worse this gets... as the suspension fights w the traction the tires are giving it... an alignment after all this will help too.

[ShocknAwe]

Check your suspension arms for slop in the bushings. If no apparent damage, then get an alignment first, cheapest thing to do.

[HP Autosport]

Check all suspension pickup points including the subframe bushings and alignment. How is your tire pressure?

[John_01]

The 135i's dodgy Rear subframe bushings are a real issue. In my opinion this aspect of the car is already faulty from the factory. Although in some way its a necessary compromise for run-flat tires. It gets increasingly worse with mileage.

Most likely a wheel alignment would be a useful improvement if you are not ready to get the rear subframe bushings upgraded. You should get the wheel alignment checked anyway because the tires will get worn on the inside edge, as the car typically develops rear toe-out after hitting pot holes.

[Cleanest135i]

Hey guys thanks for all the great input! So after reading everything I think I am going to order some subframe bushing inserts for now until I can upgrade the bushings all together and also get an alignment. I did check the tire pressure after it was at the tire shop and all the tires were at 40 psi when the max was 50 so I upped them a bit to like 46 and it seemed to help a little. I have read some good reviews on the inserts, not quite as good as the m3 bits but a definite upgrade so for the price anything will be better than the shitshow thats going on in the rear now.

[lowbudgethero]

stiffen up the rear shocks first and see if that helps

my shocks were done at 50K miles and made the car handle terribly

[Clovef]

The subframe bushing inserts will help but checking your alignment is still a good idea. If your tires feel like they are fighting with each other it makes sense that your alignment if off and your tires are fighting with each other. It should be fairly cheap to get it checked and corrected and could save you from buying another set of rear tires. Better grip would make that issue more pronounced. Also 46psi is pretty high, I would back that down some. You normally don't want to be near the max. If that is measured when cold, you will be over max after the tires sit in the sun and have been driven spiritedly.

[Cleanest135i]

Ok so I am going to stiffen up the rear shocks and I also ordered the inserts so I'll put those in and then go get an alignment and then everything should hopefully be good. Thanks for all the info.