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?

[pits]

check the wheels are actually on, if not you'll need alignment, your old tyres would have worn to the car, your new tyres are now round so maybe running on edges, toe could be out etc.

Do check your nuts though and your wheels are centred

[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.

[pits]

c3m said:

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.

Just check your wheel nuts and check the wheels are centred though, corrosion could be stopping them from sitting properly

[Collectingbrass]

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.

if it was longer then I'd get the suspension & all the bushes checked as well.

[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.

[mark.c]

Check your tyre pressures first, my money would be on them being too high. If so it will make the car feel very unstable which only gets worse as the tyre warms up further.

[Sim89]

As above, tyre pressures first then alignment.

If the RTABs, droplinks and balljoints are original (or old), they are guaranteed to be shot. E46 is a heavy car for the size and consume suspension components quite fast.

[Crafty_]

I'd get underneath and make sure they didn't jack it up somewhere they shouldn't have and broken a suspension part. Saw a post re cently where a chap had some wheels refurbished, the car got jacked up on a suspension link, which bent. Unbelievably they tried to straighten it, weakening it further and didn't mention it to the owner, who wondered why the car was all over the place.

[dgm]

It's a long time since I had my 330Ci but it was the most tyre sensitive car I've had. Different tyre makes between front and rear brought about exactly the symptoms you refer to and was solved when I put the same tyres on all round. That's not to discount the other suggestions which are all sensible.

[SebringMan]

Alex88 said:

Anything to do with the PS2 being a BMW approved tyre, and that the PS4s is not?

If that's the case the PS4s are probably lethal on my M3. I can assure you that it is not the case. The PS2 is also now a very old design albeit not a bad one.

I have to ask however, how does the car behave over white lines and cambers on the road? I ask as replacing the rear subframe bushes worked wonders on my car and cured pretty much all of the tramlining. Judging by the Redish videos the subframe bush centres corrode badly being alloy, irrespective of mileage.

When I was going down it was becoming snappy on white lines ; I always thought it was the front tyres until the bushes were changed in the subframe for SuperPro items.

But before doing anything drastic I'd check the tyre pressures. I know when I got some wheels back from the refurbishing outfit they were inflated to 45PSi! They were meant to be 36 an on a Clio!

Edited by SebringMan on Monday 22 May 21:25

[Spuffington]

It's all about the tyres.

Do a decent search across the web of E46 handling issues from around when the vehicle was launched and tyres were a huge cause of handling problems.

PS2s were an approved tyre and arguably the tyres which brought out the best balance from the chassis. The problem you've got is mixing - handling might not be as good if you had PS4s all round vs. the PS2 but on the other hand, they'll be a darn sight better than mixing the two.

I've had two E46s so can speak from experience that tyres can make or ruin these cars.

[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.

[DJMC]

Spoke to Brian at Camskill about PS4S availability for my Cayman 981 last week...

He mentioned that feedback from customers who have PS4S for other vehicles is that they are not as good as the PSS, with a softer sidewall, and as they are not recommend for track use he feels they are NOT any upgrade to PSS.

Maybe PS4 are not as good as PS2?

He's been there a while and seems to know his stuff. Give him a call?

My 2003 E46 330ci was similarly undrivable when I bought it. Bridgestones all round. Wanted to dart of the road all the time. Switched to Conti SC2 or 3 and the issue disappeared.

[Spuffington]

If you can get Michelin PSS then do so - they were amazing when I ran them on the 550i and 535d. Super grippy, composed and predictable.

[Patrick Bateman]

I'd struggle to believe Michelin wouldn't better their previous Pilot Sport tyres with the PS4 and PS4S.

PS3 not being a replacement for the PS2 before anyone says...

[HugoFastmann]

Sim89 said:

As above, tyre pressures first then alignment.

If the RTABs, droplinks and balljoints are original (or old), they are guaranteed to be shot. E46 is a heavy car for the size and consume suspension components quite fast.

This is the first thing that came to my mind too. Check all the bushes in the rear end...

[Sticks.]

c3m said:

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

Not the same as yours by the sound of it but when I had very bad tramlining on my E46 330ci with 18s, the mechanic at the dealer, who'd had several E46s himself, suggested same tyres all round, Michelins or Bridgestone. He was right.

FWIW I've recently taken MPSS off my 235i and improved the handling no end. Different tyres, different cars, no one is best for all.

[HugoFastmann]

Sticks. said:

Not the same as yours by the sound of it but when I had very bad tramlining on my E46 330ci with 18s, the mechanic at the dealer, who'd had several E46s himself, suggested same tyres all round, Michelins or Bridgestone. He was right.

FWIW I've recently taken MPSS off my 235i and improved the handling no end. Different tyres, different cars, no one is best for all.

On my E46 I had some severe tramlining for a while. I replaced the tyres all round, replaced the rear springs (one was snapped) and all the rear bushes are now poly bushes. No more tramlining.

[bmwmike]

I thought some tramlining was normal for cars with fat tyres ? My e46 did it and the severity varied a lot depending on tyres and bushes etc but it was always there.. left lane truck grooves etc. I have an f10 now and that tramlines too to varying degrees. I'd say it's better than the best I had with my e46 but it's still there.