E46 330Ci + New Rear Tyres: Unstable

[c3m]

A few years ago, I put 4xPS2s on my E46 330Ci and all was well. The rears needed replacement recently and I put on two new PS4s (255/35Y18) on the back.

Now when the car travels at speeds above 50mph, it's really unstable and borders on the dangerous at times. Sometimes it will just swing like a pendulum from one side of the lane to the other.

Yesterday, I had to brake hard from about 75 to 60 and it felt like the car was swerving: even the stability control light came on.

Any ideas how I should proceed from here?

[c3m]

Now that I think about it, I do remember getting all wheels aligned after putting the PS2s on a few years back. My plan is to get all four wheels aligned next weekend and see whether that fixes the problem.

[c3m]

Collectingbrass said:

How long between getting the tyres changed and the problem becomming noticeable? If it was incorrect fitting of the wheels I would expect it to be showing that badly within 24 hours.

It was immediately afterwards. I actually thought they were not balanced correctly, so I went to another tyre place to get the wheels re-balanced. That didn't help, so I'll get them aligned and will see where that leaves me.

[c3m]

I checked the tyre pressures, all normal. I would have gone for the PS2s again but unfortunately they've been discontinued.

I've booked the car at a local garage so it gets checked to make sure there isn't something else going on with the rear suspension (the effects can be described as downright dangerous when going over 60mph).

If that doesn't reveal anything, I'm inclined to just put 2xPS4s at the front and get both axles properly aligned.

[c3m]

Can someone recommend a good quality set of tyres that are in production today that are known to be compatible with the car and not result in the car trying to kill me on a motorway?

To note, I remember when my 330Ci used to tramline a bit depending on the surface or when switching lanes. This is nothing compared to this, when I showed the effect to a passenger, they were literally scared we would crash.

[c3m]

To provide an update, I've been travelling over the past few week so haven't had a chance to deal with the issue, so tomorrow I'll be taking the car to a nearby BMW specialist for them to take a quick look and let me know if everything is okay with the rear suspension.

[c3m]

Got the RTABs replaced, issue still present. Things actually got worse: my DSC + handbrake lights are now permanently on (amber), so will need to go into a garage to get it sorted out (happened today). I reckon it's very likely to be related to the rear end swaying after the tyre change.

About a 1.5yrs ago, one of the front callipers was intermittently seizing and failed an MOT (so replaced both at the front). I'm wondering whether one of the back ones isn't also seizing and causing the rear end to weave.

[c3m]

I still haven't sorted out the issue. I've been on a long holiday and don't want to deal with the issue any more. I might just drive it like that for a while until I replace the car with something newer.

[c3m]

I forgot to say that the handbrake + DSC light turned themselves off the next day.

SebringMan said:

But I have one question and it will sound silly. Are the tyres fitted in the correct orientation? I.e The outside of the tyre is facing outside.

Edited by SebringMan on Thursday 13th July 07:52

Not a silly question at all. Yes, I've double checked and they're facing the correct way (including the direction of rotation).

SebringMan said:

Where in the country are you exactly?

Edited by SebringMan on Thursday 13th July 07:52

I'm in the Sevenoaks area.

[c3m]

Now that I've driven with the PS4s for a while longer, I've noticed that it's very easy to break traction. For example, there's a sharp bend on a hill near my house, so I always take it in 2nd and accelerate as I come out of it.

With my previous PS2s, I never managed to get the car to slide. With the PS4s, it slides every single time.

Can bad wheel alignment after the tyre change cause such traction issues?

[c3m]

DJMC said:

You said you changed the rears, but what's on the front.

Bridgestones?

Fronts are PS2s (all four were PS2s but only changed rears to PS4s).

[c3m]

Flat6 said:

I had exactly the same issue on my E46 330ci.

Changed the rears only and certain corners which I'd take at a moderate speed on my daily commute were all of a sudden triggering the stability control. As soon as I changed the fronts so they were matching all round (Falken FK452 iirc) the problem disappeared. Was a few years ago now but the Falkens proved to be a decent tyre for both grip and longevity (seemed to be a popular tyre in M3 circles at the time too)

I might just change the fronts as well and will report back.

[c3m]

SebringMan said:

As per dhutch they have been superb with me as well.

As a final thing where did you have them fitted? The only things I can think of affecting them from the manner you've said in this thread are:

-Made in another country ; This caused an 'illegal' set of of Eagle F1s to once enter the country ; the Chinese ones were made for hotter climates that the UK (think India etc.) where they were lethal in the UK.
-Contaminated with diesel ; It's unlikely but you never know.

Got them fitted at KwikFit (not the greatest place but very close to where I live), so I think they're genuine PS4s.

One thing I found quite strange after the new tyres were fitted is how much they were are sticking out, I've never seen anything like it on another car. Can anyone confirm if this is normal?

Back tyres (PS4s):



Front tyres (PS2s)

[c3m]

ftypical said:

The rears appear to be wider than the fronts? Was this a square or staggered setup?

It's the standard staggered setup (255/35/18 at the rear and 235/40/18 at the front). Even though the PS4s are the same size as the PS2s they replaced, they do appear to be sticking out further.

[c3m]

Patrick Bateman said:

I assume you mean 225 at the front?

Yeah, sorry, 225 (just realised it's even visible from the picture).

[c3m]

Okay, so I just changed the front tyres to a new pair of PS4s, so now the whole car is running a full set of PS4s all around.

Unfortunately, the problem has not gone away. The stability control + handbrake warning lights keep switching on regularly now.

During the wheel change, I asked the garage to get the wheels aligned as well. Turns out, they were badly misaligned and furthermore, they couldn't adjust them because everything was seized.

So now I'm considering my options. I can either refresh the suspension on all four sides and keep the car for a another few years or I can just buy something else. Given the amount of hassle I've gone through, I might just drop it at a main dealer if they can sort it all out, even if it means paying a premium for the convenience of not having to keep going around garages every weekend.