86 325e Sways After Rear Snow Tire Install

[86bmw325e]

Hey Guys,

So I've done some searching and haven't found anything definite. I just recently (this afternoon) had a set of winterforce installed on the rear of my E30. They are 185/70R14 and replaced a set of bald 195/60R14. On my way home from work (bout a 65 mile drive), I noticed the car swayed almost uncontrollably on the highway and was un-drivable at 75mph. The car drove perfect before I got the new tires. I know everyone suggests rear sub frame bushings and an alignment. I have NOT had the car aligned, but I don't understand how either could be the issue when it ran fine before. If anyone has any insight, please chime in as this car is starting to eat up my budget, and I love it, but I can't afford to put anymore money into it, especially on a guess.

[berlow94]

What tire pressure are you running? Those Firestones have rather thin sidewalls...

[E30NJ]

^^^+1

[86bmw325e]

Just checked this morning, both sides are at 40 psi. Is this just something I have to live with? It makes the car completely un-enjoyable to drive

[haggardfab]

did you check if the wheels are seated properly on the hub? jack the car up and spin the wheels by hand and make sure they dont wobble..

were they new tires? a broken belt in a tire could make it feel like that too..
worse case flip the tires (front to back) and see if the car still does it or if it changes at all

[Navarone]

86 325e Sways After Rear Snow Tire Install

Define sway better. Is it like the wheels aren't tracking straight, or the shocks are blown, or the wheels are out of balance? Are the tires directional? Does it feel like driving over a metal grate bridge?

I think they raised the car up wrong and bent something.

[hippiester]

Taller tires= more sidewall flex, combined with a winter tire which generally have a softer compound would ewqual more 'sway'

[badvibrations]

Tire squirm

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=5

[LateFan]

Yeah, soft sidewalk snows on one end and summer tires on the other will act really squirrely. Like almost dangerous.

Snow tires have soft sidewalls and are very compliant for ice and bumpy snow. So one end of your car is acting normally and the other is moving around on these squishy tires and that ain't good.

You need 4 wheel snows. You still need to stop and steer when it's slick.

[86bmw325e]

Ok, Thanks for all the great advice guys! I think you're all right. I put it up on the lift and took a look at the rear subframe and trailing arm bushings. They are completely toast. I think that, coupled with the greater sidewall flex of the rear tires, is causing my swaying condition. It has gotten much better as the tires have begun their initial break in. I have a rear suspension refresh kit on the way from ecs tuning to address the rear bushings. Thank you to everyone that replied!