Not sure if anyone can help - bought a Z3 just over 2 weeks ago, nice specimen 5 years old, 50K on the clock and seemingly looked after.  The only thing is the steering seems to 'tramline' a lot.

I'm going to take it a local tyre company to check the tracking and the wheel balance, but wondered if anyone had any other ideas?

The car has 17" wheels, rather than the 16" and 225's in the front 245's on the rear.

Any help appreciated.

Tyre pressures, brakes binding, knackered tyres other than that you should find it at the garage. Is the steering wheel centred?? 1st sign of a previous nasty bang.

I have a 328i (96) and it tramlines quite bad aswell. Wheels are standard BMW alloys with 225x50(?) 16.had all tracking and suspension checked. All good,as you would hope for on a 33k car 

OK, this is where I sound dumb... What does Tramlining feel like? - I've recently taken off my standard 14" BBS rims and replaced them with standard 15" BBS rims. Pirelli P6000s on the rear axle, Dunlop SP Sports on the fronts. 205/55/15s...

Since the swap I've noticed a MASSIVE increase in understeer. I daren't put the tail out, as the car feels so unstable. Also, when braking, the steering becomes incredibly heavy.

Haven't noticed the car wandering about the road, but I think it sits in a straight line a lot better than it used to. (Must get my tracking sorted!) Balancing feels a lot better as well. Hadn't realised how bad my balancing was previously until the nice smooth ride on the 15"s.

Thoughts anyone?

Omi, what pressures do you run? With those tyres you should have ~37psi up front and a little less in the back.

Tramlining feels like the car is being pulled sideways by any ridge or in-line road anomolly.

Big tyres are a common cause as are incorrect toe angles.

Yeah the tyre pressures affect the way that the 15" wheels change the cars handling, 37psi in the front and about 32psi in the rear is the optimum, they will feel a little more understeery (made up word) as they are wider than the 14" rims therefore you are putting less pressure/square inch on the road and the tyres will loose grip on the front easier, have faith in it, if the uspension is all ok (shocks springs etc) then the handling should be better, maybe less sharp when turning in but the fact that there is more rubber on the road will improve grip in the dry.

The optimum pressure depends on a lot of factors and need to be fine tuned based on thread wear (measure with avernier, etc.). Running 37f and 32r will cause a little more oversteer as the rears will squirm under load more. Setting tyre pressures is about making sure that the sidewalls and the thread take equal roles in supporting the weight of the car. More pressure means the thread takes more of the % load than the sidewalls and v.v.

You are incorrect about the surface area though - as it remains more or less constant if the tyre pressures are kept within a narrow enough range (see above). Don't forget that the force on the ground is always the same as it is equivalant to the cars mass! It is an urban myth that bigger tyres = more rubber on the road! What actually changes is shape of the contact patch, much less its area.

I have no evidance that it makes the car more understeery - the general consensus is that at 15", the E30 is the most balanced.

The lower sidewall of the 15" will IMPROVE turn in over the 14".

Having a wider tyre can allow more channels for water drainage whilst maintaining the same amount of rubber on the road, which, depending on tyre, can improve the wet weather handling.

Dunno on this one as drving the car with the 14" steel rims and narrow tyres it feels alot sharper but if you push it hard through a bend the rear end will break away very easily (dry conditions) but with the wider 15" rims and tyres the car will take alot more to lose that rear end.  The only reason i could have seen for this was the more rubber in contact with the road theory.

The force on the ground /square inch will change with wider wheels, and the car will be more likely to aquaplane on water with wider wheels also, as thinner tyres will be more effective in 'cutting' through the water to reach the tarmac below, the wider tyres will trap water easier in the centre of the tyre.

Wider tyres can be better in the wet as you say but it does depend alot on the tyre make and the design of the tread as you also say but i have always found that a car with narrower wheels will perform better in the wet.

Paul,

Can you explain what you mean by "The force on the ground /square inch will change with wider wheels".

Narrower tyres are less prone to aquaplaning in principle but a wider tyre can accomodate much better thread patterns to make up for it. Nowadays, there is not so much of a difference - and in damp conditions, the wider tyre will be often better.

Kitty,

Nice resolution.

The force in contact with the ground has got to be diferent, the same weight but spread over a larger area, must put less pressure down on the road in any given area say a square inch. 

As for the wider tyres not being so good in the wet that is just from my personal experience, i have driven alot of cars and found that in general the ones with a narrow tyre fittet perform better in the wet, the damp is slightly different and i agree with your statement on the tread patterns there, i have just always found wider tyres to stay more squared when cornering and lead to the car sliding more easily.  

And glad to hear the stealer sorted you out Kitty, they can be nice sometimes. 

No, the weight of the car is the same so the force in total is the same. If the tyre pressure is the same, from P=F x A (pressure = force x area), the area will be the same too. What happens is that the shape of the contact patch changes. A narrow tyre has a contact patch more along the length of the car and a wider tyre has a contact patch more across the car. The area will be almost identical.

This is not 100% correct because the sidewalls will play a different supporting role (and tyre pressures are usually higher on wider tyres because of this), but the point is that it is an urban myth that bigger tyres give a bigger contact patch.

If you put on truck tyres, they would hardly deflect at all - you would almost have point contact!

Regarding the wet, my exprience is different. I don't have enough information about aquaplaning, but in damp conditions I have always found bigger tyres to be better. Usually they are better quality too! Try and find some braking tests within a model range. You will find that the car with the bigger tyres brake better - even thought they have the same ABS systems.

Your point about wide tyres squaring to the road needs to be tempered by the fact that you will get less roll before they skid because they will slide at a lower cornering force. Your point also suggests that it is NOT advantageous to have the tyres squared to the road too - or have I picked that one up wrong!?

Hi newbie here, Just a quick note,

My e36 coupe tramlines all the time.

Tyres at the rear are 235 x 40 x 18

After chatting to many other BM owners, I am informed that most rear wheel drive car with wide back tyres tramline..

I've now had an 02 320d Touring for a whole week (std 16" wheels) and am finding I feel indentations in the road etc - not sure I'd quite go so far as to call it tramlining as such - much more than in my previous Audi A3. I suspect it may be just that the Audi didn't have steering feel, but any thoughts?

Ian

Having done a bit more driving now, it definitely seems a bit funny - twitches noticeably over lumps and indentations, follows ruts and pulls slightly but definitely to whichever side the camber is running down on.

Any views on if this is normal and/or whether there's anything to be done to correct it?

Ian

Can anybody remember what the claimed optimum was for the E30 325i on 15s?

It was in the newsletter a while ago, something like 37 for the rear and 32 for the front.  If thats right, thats set up for more understeer than over?

I'll have to experiment with them once i've fixed the subframe boshes, its a bloody death trap at high speeds, been out to much recently haven't had a chance.

What the hell are you lot going an about!

If you manage to notice the difference between 2 psi here and 2 psi there on a uk road then your'e a genious.

I think you'll find that because of the average uk road surface you could probably run with flat tyres and still experience tramlining or whatever.

Pikey

B318sp - oh I see. I think it becomes more difficult to calculate the correct tyre pressure on aftermarket alloys (thats is different size ones).

with a 195/55R 15 the correct tyre pressure by the manufacturer could be, say, 32 psi. But with a 205/40R 17 is the tyre pressure the same? Does the tyre contain the same area for air to be in?

It all gets a bit complicated and best left to track tinckering, but I agree with b318sp try it and see, until you get the best result for you.

Good Luck,

Pikey

I was on another forum on the internet recently and a similar debate was discussed regarding tramlining with reference to the new 330. From the opinions that were exspressed different tyres seriously affect tramlining as modern low profile tyres usually have very hard side walls which don't deviate on bumps and thus tramlining occours as well as those discussed regarding wheel width.

My exsperience is that pirelli's and Dunlops can suffer badly from this, whilst other companies like Michelins and Uniroyles and Bridgestones are less prone.  I have a six which runs of seventeens and have found Uniroyles to be excellent, and have not exsperiences any problems with tramlining so would recomend these.

Worn suspension componentry can be another factor, and if your car has done more than 60k suspension will be begining to get a little tired and a change of dampers will make a big difference.

Anyway hope this helps

Regards

Just been to the local dealer with my year-old 320d Touring (200 yards away - a lucky side-effect of switching to BMW) and he reckons it's had new suspension arms as they look v squeaky clean - and that they've not been aligned correctly, as the (new) tyres are wearing on the outer edge.

He reckons it's got too much toe-in, whereas I'd thought toe-out was more likely to make it inclined to turn too easily, but hey the upshot is it needs wheel alignment checking and I've just got to persuade the dealer I bought it from 3 weeks ago (closer to 200 miles away - well, 130 at least) to cough up.

Ian

Oh this is getting technical!

Pikey

Well, mine had its wheel balancing (didn't work the first time as front tyres had been so worn down they couldn't get a fix, so had to rebook and confirm that the dealer I bought from would give me new tyres too) - but still not right.

It doesn't actually go off-line by itself any more, but whenever the road surface has any imperfections the steering lightens and wobbles so that it's very easy to accidentally direct it off course (but if left alone it does in fact keep going straight ahead); and under acceleration or braking on a poor road surface again it all just feels wobbly - without actually taking itself off-course.

Suspect it's going to have to go back for another check... but any ideas?

Ian

Well, the lower front suspension arms have been replaced (I think that's what they said) and there's no play in the steering generally; on a lovely smooth road surface it seems fine, but on a dodgy road surface it comes over all wobbly - at high motorway speeds and slow town speeds alike.

Having had a wheel alignment once I guess I probably need to get someone from the dealership out with me to see what they think...

Ian

Just to get back to the difference a tyre can make.

I have 215/40/17 tyres on the front of my car (and the back for that matter ). I have used a couple of sets of Bridgestone SO3's now, and as much as I like them, they did used to tramline like crazy. I was advised to try the new Goodyear F1 GSD3 to cure (or at least reduce) the tramlining problem.

Now I have the Goodyears fitted (same size, same pressures etc). The tramlining has virtually dissapeared. This just goes to show that different tyres of the same size can indeed make a big difference.

Cheers,

Ian.

Use same width tyre all round, what width are your rims? I use 235/40 on an 8x17". Dunlop SP9000 Sports are good tyres for a 2.8, I use 'em wid no probs. The end.

Well, had a road test with a BMW technician yesterday and couldn't find anything wrong except tyre pressures, which were too high (34/39 psi f/r on std 16" wheels - should be 31/37 apparently). Does make a difference, but suspect that was exacerbating rather than creating the problem.

But they took it up on the ramps and checked the suspension bushings for wear and there isn't any, no play in the steering, full wheel alignment all done. It does run straight, so I don't think there's anything knocked out of place; but just steering wheel rocks over bumps (before returning to straightahead OK), steering lightens up on bad roads at any speed, making it easier to steer off course accidentally; and whole car feels wobbly when braking on rougher surfaces.

Running out of ideas... the only thing is when they talked me through the wheel alignment they didn't actually specify what the castor was and should have been and had been adjusted to etc, unlike the camber and toe-in which were causing the obvious problem. So I wonder if this got overlooked? Anyone know if it would be a likely cause of this sort of problem?

Ian

OK, back to the garage again last week. New technician reckons it's a characteristic and he's had 5 or 6 customers notice it. Well maybe it is but I must say I hope mine's worse than most, because I can't believe BMW 3-series would keep on winning every single group test in any magazine if they all wobbled like mine does when the road gets bumpy!

As stated before, I've only got 16" wheels on there, and the steering wheel kicks back and forth in your hands over bumps even though the car still does end up going straight.

Still wondering about the castor, although maybe the tyres (Dunlop SP2000) aren't helping? Presumably some tyres might be more likely to be affected by bumps, eg. stiff sidewalls might make them deflect more readily?

Ian

Ian, I have spoken to several other E36 owners and they have had similar experience. On my vehicle the trait only shows up when you hit a pothole, some badly damaged tarmac or the road is just generally bumpy. It does mean that there are some roads round where I live that I just don't drive fast along any more as its just not enjoyable. I thought the same thing as you, but I guess its just because on the continent the roads are a lot better.

My last car was a Nissan Primera SRI and even with the sports suspension the ride quality was better than my BMW, although it was on 185/65/14s!

I should have finished of my last post by saying that this trait may be the price you pay for having such comunicative steering. I have never driven a car that provides you with so much information about the road surface and levels of grip availible. The fact that it puts me off thrashing down roads with pot holes and poor surfaces is to be honest probably a good thing. Crashing through potholes can't be good for the suspension and if the surface is poor then the way any car will behave can become unpredictable which is dangerous.

As for tramlining, any car on 225 tyres is going to do this.

Kevin,

Which Falkens do you have on? I need to get shot of the Pirellis I'm running on the back of mine before I do something daft