Tyre brand advice please

[RichardG]

You are confusing me continually referencing to 2 suspension settings.
Would you care to elaborate there was 2 different suspension options available depending on the model, on release the 2.5SE had standard suspension and the 3.0SE M Sport suspension which was 15mm lower and stiffer but no E85/6 suspension is switchable, the sport button has NO effect on the suspension.
I ditched the runflats for Falkens long beofre I ever became involved with this forum and have never for one minute regretted it. Though I now need 4 new tyres and am going to try something different.

[Nigel-Z4]

RichardG, the suspension is set up at the factory in a different way with softer springs etc for run-flat cars. If you specify when ordering a new one that you want non run-flats, it comes out of the factory with different suspension settings and harder springs. If it has run-flats, it was designed for run-flats.

The sport button does have an 'electronic' effect on suspension, according to BMW. It changes the characteristics of when the car changes gear in auto models and the ride gets stiffer; don't ask me how, just what BMW told me. Perhaps phone your local dealer and ask them as that way you will get it from the horses mouth and it will be accurate information.

[mmm-five]

I'm almost inclined to take gannets advice and look at replacing the rear two (which are getting close to legal limit) with the Michelin PS2 ZP run-flats. Well, PS3 anyway as the PS2 have just been discontinued, PS3 is the replacement.

My front tyres are Goodyear and a Bridgestone, and are like new. So in a thousand miles, I'll replace my worn rear ones with the PS3 ZP run-flats and see if that half helps, then when the front need it in 20,000 I'll match all for with two more PS3 ZP's

I know you probably won't listen to a word I say, as your tyre expert/dealer/mother-in-law has told you otherwise, but the PS3 IS NOT the replacement for the PS2.

The PS2 is replaced by the better performing PSS. The PS Exalto is replaced by the PS3.

Going from a PS2 to a PS3 is a DOWNGRADE!

BTW, this info is on the Michelin website if you'd care to look - but then again, they're only the manufacturer so probably know jack

[mmm-five]

You are confusing me continually referencing to 2 suspension settings.
Would you care to elaborate there was 2 different suspension options available depending on the model, on release the 2.5SE had standard suspension and the 3.0SE M Sport suspension which was 15mm lower and stiffer but no E85/6 suspension is switchable, the sport button has NO effect on the suspension.
I ditched the runflats for Falkens long beofre I ever became involved with this forum and have never for one minute regretted it. Though I now need 4 new tyres and am going to try something different.

Don't bother trying to understand him.

He came on here asking for advice and then claims to know it all because the dealer/friend/tyre fitter told him the 'truth'. We're all obviously part of a conspiracy against him

He doesn't seem to understand that the only for suspension on an e85/e86 (whether it was ordered on runflats or not - which I think he's getting confused with the current model) were standard or M-Sport. The ///Ms had different suspension too, but that is a different car and only had 1 spring set for the coupe and 1 for the roadster.

In one breath the dealer states that Z4 wheels are only suitable for run-flat tyres, and in another they claim to have different spring/damper settings for run-flats vs standard tyres.

I'd just let him get on with it and let him find out the hard way.

[ZermattV]

Not entirely sure i go with the main dealer knows best approach based on some of the conversations I've had with them ... one even asked me how do you clean out the rear gutters on a z4 ...

[Finisterre]

I'd just let him get on with it and let him find out the hard way.

I was pretty dubious about Nige by post 5

Amateurs do stuff for Love.
Professionals do it for the Money.
Independent Scientific do it for Truth.

I am fairly sure BMW dealers are the least trustworthy.
You have to understand context before you assign value.
TBH I am surprised BMW were ever in the running.

[dgm]

If there's one thing to take away from this thread Nige it's that BMW dealers and tyre fitters talk through their arse on technical matters most of the time. The knowledge on here is actually very good, choose to ignore it at your peril.

[Robb]

I'd recomend the Kumho's too, think someone mentioned them earlier.

I had the Ku31's on my Z but i think the newer Ku39 is about now.

If your only concern is insurance why dont you ring them up and ask, I told mine and they couldnt care less as long as they were the correct size and speed rating.

Spring rates are frequently changed independantly to tyres and vice versa, it will all combine to effect the characteristics of the drive but unless you do an enormous chance you wont find yourself outside of the safety envelope.

Your car isnt going to lose grip and dump you in a hedge because you've fitted non-runflats.

Think of another example, if you had a ZM which comes with standard tyres and when replacing you fitted with £14 plaggy ditch finders, they would be considered the correct size, type and speed rating but you would likely end up in a ditch. Yet if you fitted some runflats you would be alright?

Im currently using the spare front run flats off my Z4 on the rear of my E46, difference in ride = minimal. Good year non-runflat fronts.

[tomscott]

You are confusing me continually referencing to 2 suspension settings.
Would you care to elaborate there was 2 different suspension options available depending on the model, on release the 2.5SE had standard suspension and the 3.0SE M Sport suspension which was 15mm lower and stiffer but no E85/6 suspension is switchable, the sport button has NO effect on the suspension.
I ditched the runflats for Falkens long beofre I ever became involved with this forum and have never for one minute regretted it. Though I now need 4 new tyres and am going to try something different.

Don't bother trying to understand him.

He came on here asking for advice and then claims to know it all because the dealer/friend/tyre fitter told him the 'truth'. We're all obviously part of a conspiracy against him

He doesn't seem to understand that the only for suspension on an e85/e86 (whether it was ordered on runflats or not - which I think he's getting confused with the current model) were standard or M-Sport. The ///Ms had different suspension too, but that is a different car and only had 1 spring set for the coupe and 1 for the roadster.

In one breath the dealer states that Z4 wheels are only suitable for run-flat tyres, and in another they claim to have different spring/damper settings for run-flats vs standard tyres.

I'd just let him get on with it and let him find out the hard way.

Again you've nailed it on the head here mmm-five. The only spring types on the Zds were SE, M sport and the M springs on the Z4Ms. Run flats have been around for a few years to create a hybrid the best of both worlds so if you have a puncture it alows you to drive 60 miles to get a replacement tyre. But this compromises handling and ride. You just have to look at the serious BMW cars like the Ms and they all come with run flats... wonder why that is...

BMW go by the book and employees are trained to read computer screens and manuals which is where you are getting your advice from.

Funny recently I had my key functions changed on my car and the driver window would go down by itself when the car was locked and at random times. Now I said to them it only started happening when the functions were added, but apparently my window motor was a dudd... although it worked perfectly so they replaced it. Instead of just re-setting the computer and re initialising the functions they replaced the motor and guess what!! the problem persisted. Sent it back.. they replaced the whole computer module and started from scratch which suited me because it meant thats one less thing to go wrong in the future and the warranty paid for it. But really shows how much BMW dealers know.

As you have heard from numerous members on here who have done exactly what you were asking about with 0 problems, and you are now arguing they are wrong because BMW are scare mongering you into not doing it. Just do it and if you dont like it then put RF back on the car when they need replacing or sell them to someone who wants them.

IT IS NOT GOING TO MAKE THE CAR DANGEROUS! its absolutely ridiculous! Non RF tyres have been around for over 100 years and guess what... no problems.

BMW will tell you to put them on because they cannot admit to their mistake of putting them on in the first place and ruining the car.

[sars]

Nigel read the manual, it states that only tyres recommended by BMW should be fitted, the key word here is should and not must. RFT's are fitted for your safety, however the owners manual does not state, anywhere, that RFT's must be fitted. If there was such a danger in not doing so, it would be plastered all over your car, they would have to make all reasonable steps to highlight this.

The only tyre recommended by BMW for the Zed are the Bridgestone RE050 RFT, if you are fitting any other model this is against their recommendation.

You are indeed correct that BMW's are developed from the outset to run on RFT's which as we all know have stiffer side walls, and as mmm-five has already stated, the side wall stiffness will vary according to profile, a lower profile equates to a stiffer side wall. So the engineers will evaluate/develop the ride on different size wheels, giving a band of tyre stiffness available, plus a hefty safety margin.

The upshot of this is that you can run non RFT's without destroying the handling by compensating the lower wall stiffeners by using a reinforced tyre and increasing the air pressure slightly.

This forum is a great collection of minds and experience, ultimately it is your call on what you do, the safe bet is to replace with Bridgestones, for me though dropping the RFT's was an easy decision made through logic and experience

[RichardG]

RichardG, the suspension is set up at the factory in a different way with softer springs etc for run-flat cars. If you specify when ordering a new one that you want non run-flats, it comes out of the factory with different suspension settings and harder springs. If it has run-flats, it was designed for run-flats.

The sport button does have an 'electronic' effect on suspension, according to BMW. It changes the characteristics of when the car changes gear in auto models and the ride gets stiffer; don't ask me how, just what BMW told me. Perhaps phone your local dealer and ask them as that way you will get it from the horses mouth and it will be accurate information.

Nigel I have no idea where you are getting your information from but please stop going there before they kill you.
I bought my 2.5SE Z4 new in 2004 and no point was I ever offered the option to change the suspension to suit Non-RFTs the only option was to upgrade to the same M spec springs as fitted to the 3.0SE, if you are being told differently then that person is a LIAR.
At no point in time was the E85/6 fitted with electronic dampers you can press every button in the car and you will NOT change the damping rates, again if you being told that pressing the sport changes the suspension in any way then that person is a LIAR.
http://www.z4-forum.com/forum/viewtopic.php?f=2&t=24559 Here is alink from Pawnsacrifice to just about every manual printed for the E85/6 try reading them and you'll find the info you are being offered here is right and that your dealer / experts are as far from the truth as it possible to be.

[srhutch]

Dealers will even take back E85/6 with non runflat tyres and sell them on without changing. I talked to two dealers when I was looking to part ex mine with Falken 452s and they just said they would stick a mobility kit in the boot.

[a11y]

Wow. This thread. Just wow.

[ASW28]

Again you've nailed it on the head here mmm-five. The only spring types on the Zds were SE, M sport and the M springs on the Z4Ms. Run flats have been around for a few years to create a hybrid the best of both worlds so if you have a puncture it alows you to drive 60 miles to get a replacement tyre. But this compromises handling and ride. You just have to look at the serious BMW cars like the Ms and they all come with run flats... wonder why that is...

Did you mean Non - RunFlats ?

[Nigel-Z4]

I thought M's ran on non run flats as well?

dgm, saying "BMW dealers and tyre fitters talk through their arse on technical matters most of the time. The knowledge on here is actually very good, choose to ignore it at your peril."

Have you any idea how crass that sounds.

Finisterre, why are you surprised BMW are in the running, they only build the bloody car, I think they know what they are talking about, again, duh, the mind boggles.

Sorry mmm-five, but who would you believe, a respectable tyre dealer called Performance Tyres in Huntingdon, and two respectable BMW dealers, Elms in Bedford and Murketts of Huntingdon, or, er, a bunch of blokes on the web, duh, it's a no brainer to me dude. Sorry not to listen to you, but you hardly sound professional now do you??? If you really do know what you are talking about, which I seriously doubt, try doing so in a professional diplomatic way. Firing off like a chav gives you zero credibility.

Now, I'm sorry if I'm frustrating you guys by listening to tyre fitters and BMW, but just step back for a minute and look at the abuse coming form some of you guys, and you wonder why?