Run Flats or Not Run Flats

[IanzZ4]

Hi, I'm new to this forum and Z4's so bear with me and forgive my bad grammar.

I'm 59, been a keen car fan all my life. My stand out car to date is a genuine T reg twin head light Mk2 Ford RS2000. Not having the silly money they go for nowadays I opted for a roadster, so putting a tick in another motoring box.

I picked up a 2012 Z4 20i S Drive M Sport with full service history from a dealer a few weeks back and to be honest I'm really not happy.

I have a 70 plate 320i and a 2016 Range Rover Sport and both handle far, far better than this Z4. It seems to be unattached to the road, especially and most disconcertedly when at speed. It's really quite scary, requiring continuous steering inputs to travel in a straight line. I've set the tyre pressures and had the wheels aligned on a Hunter laser rig, but its made little to no difference.

Having joined your forum, I can see I'm not alone with this experience, however what I can't see here is definite reason and solution.

My example has done 75k miles and is fitted with newish run flats of the correct size. Fitted before I bought the car, there are mis-matching Yokahamas on the front and Churchills on the rear. Are they the cause? Some of you say yes, some say no. Cost to me £450 to try!

Then I see a mention it could be the power steering motor. Cost to me £800 for refurb to try! Is it that or isn't it?

Or is this just how an 11 year old BMW drives and my 320 will feel the same when it reaches the same mileage. I suspect that's not the case.

Anyone able to advise me for sure please?

Best regards

Ian - Newbie of Essex

 

[inkey$]

My example has done 75k miles and is fitted with newish run flats of the correct size. Fitted before I bought the car, there are mis-matching Yokahamas on the front and Churchills on the rear. Are they the cause? Some of you say yes, some say no. Cost to me £450 to try!

Welcome to the forum, Ian.

I say this with the greatest of respect; you're going to need to spend some money on the car. As a starting point, you need to sort this horrific tyre setup out - get yourself a complete set of non-runflats (even midrange if price is an issue) and stat - regardless of the £450 bill (cheaper if you can get a good BlackCircles or MyTyres deal). It's very likely doing the car no favours at all and I think you'll find its a big improvement.

Am sure others with E89 experience may come along and help with other suggestions, but thats the direction I'd take first as a process of elimination that conveniently would make the car safer, ride better and arguably add value.

 

[Chippie]

Hi Ian
I’d have to agree with Inkey$ regarding getting a decent set of matching non run flats and see if that improves things.

 

[Silverstar]

I have a 70 plate 320i and a 2016 Range Rover Sport and both handle far, far better than this Z4. It seems to be unattached to the road, especially and most disconcertedly when at speed. It's really quite scary, requiring continuous steering inputs to travel in a straight line. I've set the tyre pressures and had the wheels aligned on a Hunter laser rig, but its made little to no difference.

Hello and welcome to the forum! Mine is now 14 years old and most definitely does not drive like that, dead steady in a straight line. I ditched the runflats the next day after I got my car, as has already been said a good set of non run flats would be the first step to take.

 

[Pondrew]

Hi Ian,
Run flats vs non RFTs......nearly as many opinions as which tyres are 'the best'.

If your car is as bad as it sounds then it isn't the tyres, it's something else. Suspension would be the first place to check IMHO.
I have a 10 year old E89 on run flats (albeit matching Bridgestones) and apart from the rather harsh ride it handles absolutely fine and dandy, with no issues whatsoever.

I don't agree with the "yeah start by changing your tyres at a cost of £xxx, it may help a bit" attitude. :x

BTW my best mate put his 1979 Mk2 RS2000 into a tree at 70mph back in the day. Engine landed on the passenger seat. Luckily he was alone at the time. So they were not terrific handling cars!

 

[B21]

As usual I would suggest you ignore Pondrew's advice!

A 10 year old 75k mile 20i MSport should not be that bad..

As others have said the first step is a matched set of non ditch finders..if you don't want to go 'premium' there are many sub premium brands that would suffice..

Having said that if you are not willing to spend £400-£500 on decent tyres then maybe its not the car for you.

There are of course many possible issues..had you said that you had a perfecr set of properly inflated premium tyres then yes you could look at worn suspension parts..however a decent tracking centre would notice suhc things as alignment could prove difficult..

SO GET THE FRIGGING TYRES CHANGED PRONTO!!!!!

 

[enuff_zed]

Welcome aboard Ian.
Firstly, the power steering motor issues are mostly confined to the earlier E85 model, so not your problem I wouldn't think.
Whilst I agree that it is an expensive experiment, so it would be to start digging into suspension etc as well.
So start with some simple basics.
1. Do you mean the two Yokohamas on the front are different patterns? That may not help.
2. Check the sizes front and rear as well, in case an error has been made there. You don't say if you have 18" or 19" wheels, but they should be staggered, wider at the rear. Let us know the figures.................... and don't assume someone has got it right on both sides, so check all four!
3. Ask nicely on the forum and you 'may' find someone near you with a decent set of wheels/tyres you could borrow, to see if tyres are indeed your issue. Even just a pair of matched non-runflats on the front for a test could prove the point, though I personally wouldn't advocate mixing those with rear RFTs as a long term solution.
4. What tyre pressures have you set? Try experimenting with those a little. Even before I swapped to non-RFTs I found my car handled better with slightly lower pressures. It seemed to be more sensitive to changes on the front than the rear.

 

[Pondrew]

As usual I would suggest you ignore Pondrew's advice!

Two words Peter....just two. I'll let you guess what they are! :|

 

[B21]

Welcome aboard Ian.
Firstly, the power steering motor issues are mostly confined to the earlier E85 model, so not your problem I wouldn't think.
Whilst I agree that it is an expensive experiment, so it would be to start digging into suspension etc as well.
So start with some simple basics.
1. Do you mean the two Yokohamas on the front are different patterns? That may not help.
2. Check the sizes front and rear as well, in case an error has been made there. You don't say if you have 18" or 19" wheels, but they should be staggered, wider at the rear. Let us know the figures.................... and don't assume someone has got it right on both sides, so check all four!
3. Ask nicely on the forum and you 'may' find someone near you with a decent set of wheels/tyres you could borrow, to see if tyres are indeed your issue. Even just a pair of matched non-runflats on the front for a test could prove the point, though I personally wouldn't advocate mixing those with rear RFTs as a long term solution.
4. What tyre pressures have you set? Try experimenting with those a little. Even before I swapped to non-RFTs I found my car handled better with slightly lower pressures. It seemed to be more sensitive to changes on the front than the rear.

I suspect Yokohamas on the front and ‘Churchills’ on the rear is not a match made in heaven?

 

[enuff_zed]

I suspect Yokohamas on the front and ‘Churchills’ on the rear is not a match made in heaven?

They will fight them on the beaches, in the hills and on the streets.'

 

[inkey$]

I suspect Yokohamas on the front and ‘Churchills’ on the rear is not a match made in heaven?

^ this. And if you’re keeping the car then re: my first post on the subject, why not get a decent set of tyres on it to start with?

 

[Silverstar]

Just a thought but if the car is not running correctly and you suspect that there is a mechanical problem, seeing as you just bought the car from a dealer why not go back to them and let them figure it out and hopefully fix it. As per your statutory rights you have 30 days to reject the car for any fault found and upto 6 months to get the garage to fix the problem unless they can prove that the problem did not exist at the time of sale.

 

[inkey$]

I now understand why the OP thinks there are conflicting viewpoints on all of this :lol:

 

[sp3ctre]

Hi, and welcome to the forum. It does sounds remarkably similar to my original Z4 with the sticky steering, but as others have said, this should not affect the e89.

Personally I would put some decent rubber on it, regardless of this situation.... it's one of the most important things for a performance car of any make.

That said, the ideal situation would be to drive an e89 that is setup correctly and drives well, so you can feel the difference. That way you may be able to get a bit more of a clue to the issue. Maybe a BMW specialist garage that is familiar with these vehicles may be able to help?

 

[Mr Tidy]

Hi Ian and welcome from a former S plate MK2 RS2000 owner.

I'd try asking the dealer first, but if you don't get anywhere with that maybe you could reject the car?

I've not had an E89 and although one of my E86s was a bit twitchy it still felt much more planted than my RS2000 did despite being on (matching) runflats!

If you do persevere I'd start with a decent set of matching tyres (non fun-flats seem to be the preferred option) before getting too involved in suspension wear, alignment, etc.

But that's just another opinion and everyone has one, a bit like................!

Good luck anyway, Iain.

 

[ronk]

A previousE89 of mine with low mileage was absolutely fine at U.K. speeds but was not an easy drive in Germany- at 120 it was a constant battle and it did not instill any confidence - it was running on the standard run flat rubber

This current car is on the supplied rubber and at 145 it feels very very planted (only the speed limiter in the LH seat prevented any increase)

I’m sorry if that muddies the waters - but I suspect the instability comes from the budget tyres

 

[IanzZ4]

Hi again and thanks to everyone for your advice.

Well the consensus of blame seems to point to the RF tyres and their varying performance.

To be clear it's matching new RF Yokahamas on the front and matching RF Churchills (fight them on the beaches - HaHa very good) on the rear, on the std M Sport 18" rims, 255/35 rear, 225/40 front. Rather unhelpfully somebody has ripped the important part of the tyre pressure label off the door jamb. My 320i has factory fit Potenza RF's same width and profile front and rear, just 19" instead of 18" so used BMW's recommended 2.3bar front and rear for them as a starting point.

Before I commit to spending £500 on a new matching set of non-run flat tyres, I've booked the car in to my local Indy BMW workshop, Hallmark Autos of Maldon (any one know them?) on Monday. I've asked them to carry out a thorough inspection of the car, which should show up any hidden defects.

The dealer I bought it from, View Autos, did their own pre-sales check and an oil service, but I will feel happier with my own independent assessment.

Thanks for your valuable advice and please watch out for my next post after Monday's visit to the workshop.

Best regards

Ian

 

[axelleveau]

Hi Ian,

I am guessing you meant 225/40 at the front and 255/35 at the rear? (havign the 35 and 40 mixed up?)
2.3 bars front and rear seems fair to me but I am not used to RFTs so they might need a touch more

I think your plan to get it inspected first is fair, at least you can have piece of mind there is no serious suspension issue or even a leaking damper.
I would advice getting the alignment checked, regardless whether you end up changing tires or not you should get it done so you cannot really loose there.

And then take it from there, if ride is harsh then change tyres, otherwise keep it as is

 

[enuff_zed]

Just looked at mine in the garage. Can't get a decent photo due to the light, but:

225/40 Front = 2.5 bar
255/35 Rear = 2.7 bar

I'm now on non-RFTs and prefer PSI, so after much experimentation I'm running them 34psi front and 36 psi rear.

Hope that helps?

 

[Busterboo]

Just looked at mine in the garage. Can't get a decent photo due to the light, but:

225/40 Front = 2.5 bar
255/35 Rear = 2.7 bar

I'm now on non-RFTs and prefer PSI, so after much experimentation I'm running them 34psi front and 36 psi rear.

Hope that helps?

Preferring PSI, as I do, or not, 2.5 bar is approximately 36 and 2.7 bar is 39.