Urgent advice - runflats or not. Staple in tyre!

[cj10jeeper]

Here we go a couple of shots of a standard OEM 108 rim showing a perfectly normal bead seating profile and a couple of extra ridges to keep the flat tyre centred. So if anyone tell you they are made different and normal tyres won't fit you know better

 

[cj10jeeper]

As said, the rim is only different in that it makes a concession for an RFT *ontop* of functionality for normal tyres.

It doesn't then preclude the use of non-rft's...

From a professional tyre fitter I spoke to, the main difference is that it is simply a non-symmetric interior shape where you can push the tyre off the bead more easily because there is more clearance to allow so (with the thicker walls). You can still fit an RFT to a non-rft rim, it's just harder to get on/off...

From what I have gathered from much reading, the rim concession is *purely* for this purpose, ie, ease of fitment. A normal tyre should go on and off and operate exactly the same as any rft tyre on that rim!

Dave

Dave - interesting that you have it that it's for ease of fitment. Not challenging your research, I just wonder how it would make fitting easier as the bead is always dropped into the channel to remove, but either way the normal tyre to bead seal is the same so in driving use they are just fine.

 

[Mr Whippy]

As said, the rim is only different in that it makes a concession for an RFT *ontop* of functionality for normal tyres.

It doesn't then preclude the use of non-rft's...

From a professional tyre fitter I spoke to, the main difference is that it is simply a non-symmetric interior shape where you can push the tyre off the bead more easily because there is more clearance to allow so (with the thicker walls). You can still fit an RFT to a non-rft rim, it's just harder to get on/off...

From what I have gathered from much reading, the rim concession is *purely* for this purpose, ie, ease of fitment. A normal tyre should go on and off and operate exactly the same as any rft tyre on that rim!

Dave

Dave - interesting that you have it that it's for ease of fitment. Not challenging your research, I just wonder how it would make fitting easier as the bead is always dropped into the channel to remove, but either way the normal tyre to bead seal is the same so in driving use they are just fine.

Hmm, your picture clearly shows the channel back from the seat to keep a deflated RFT's sidewalls sat about where they should do

From what I heard, the rim shape is non-symmetric though, so I *think* that channel/groove ends for a little while around the rim. That is simply for ease of removal of the rft by giving it a channel that can be pressed through to 'get it going'

Either way, the rim is perfect for any tyres, it just has a *concession* for RFT ontop of normal tyre functionality

Dave

 

[cj10jeeper]

Dave - Just checked and the profile is consistent right around the rim, so I'm doubting that it is made in any way to ease removal. All interesting but academic to the key question of it non RFT's can be fitted on RFT rims, which seems to be consistent that they can.

 

[Mr Whippy]

Dave - Just checked and the profile is consistent right around the rim, so I'm doubting that it is made in any way to ease removal. All interesting but academic to the key question of it non RFT's can be fitted on RFT rims, which seems to be consistent that they can.

Oh rly

I was just going on what I had been told. Either way then, it seems sensible to query even more the idea that non-rft's can't be used on rims that come oem with an rft tyre.

I've fitted lots of tyres in my day, and there is nothing different there to any normal wheel, except a second lip to STOP (a concession) a flat rft tyre from collapsing in on itself defeating it's purpose as a "run on flat" tyre.
Indeed, it's likely that a stiff non-rft tyre will actually run better on these rims when flat anyway

Dave

 

[Lewi]

I would say to change them, I changed mine not long after having the car. I think it makes the car handle much better, they they take out all the little bumps in the road too. As for the wet you get alot more grip with standard tyres over the rf for sure.

 

[Batman]

Thanks very much for the advice guys

 

[a11y]

So, are you changing to non-RFT after all this chat?

 

[Batman]

YES!! They'll be on the car this time tomo.

Also - has everyone notified there insurance companies when they've done the same?

 

[cj10jeeper]

Dave - Just checked and the profile is consistent right around the rim, so I'm doubting that it is made in any way to ease removal. All interesting but academic to the key question of it non RFT's can be fitted on RFT rims, which seems to be consistent that they can.

Oh rly

I was just going on what I had been told. Either way then, it seems sensible to query even more the idea that non-rft's can't be used on rims that come oem with an rft tyre.

I've fitted lots of tyres in my day, and there is nothing different there to any normal wheel, except a second lip to STOP (a concession) a flat rft tyre from collapsing in on itself defeating it's purpose as a "run on flat" tyre.
Indeed, it's likely that a stiff non-rft tyre will actually run better on these rims when flat anyway

Dave

Lucky I actually have one in the garage to look at unmounted. Such threads are always interesting as I've got them fitted so it's nice to understand better.
I hate these urban myths that grow up from part information by tyre shops :thumbsdown: It would however be great to get an 'expert' opinion from someone at Bridgestone or say BBS as to how it all works

 

[a11y]

YES!! They'll be on the car this time tomo.

Also - has everyone notified there insurance companies when they've done the same?

I've notified mine (despite not actually fitting them quite yet - they're in my garage but I haven't had the time yet...) and they didn't charge me any extra. They did put a note on my file though saying that I'd advised them of that. I'm with Esure if that helps.

It's a non-standard part so worth telling them, just to be on the safe side IMO.

 

[Mr Whippy]

Dave - Just checked and the profile is consistent right around the rim, so I'm doubting that it is made in any way to ease removal. All interesting but academic to the key question of it non RFT's can be fitted on RFT rims, which seems to be consistent that they can.

Oh rly

I was just going on what I had been told. Either way then, it seems sensible to query even more the idea that non-rft's can't be used on rims that come oem with an rft tyre.

I've fitted lots of tyres in my day, and there is nothing different there to any normal wheel, except a second lip to STOP (a concession) a flat rft tyre from collapsing in on itself defeating it's purpose as a "run on flat" tyre.
Indeed, it's likely that a stiff non-rft tyre will actually run better on these rims when flat anyway

Dave

Lucky I actually have one in the garage to look at unmounted. Such threads are always interesting as I've got them fitted so it's nice to understand better.
I hate these urban myths that grow up from part information by tyre shops :thumbsdown: It would however be great to get an 'expert' opinion from someone at Bridgestone or say BBS as to how it all works

I was told the rft rims were non-symmetric by a provider of tyre fitting equipment and long time tyre fitter person. It's possible that maybe they are evident on some wheels but not others.

Either way, the idea that normal tyres are no good on them just can't hold true because they would literally make them incompatible to prevent accidental misuse (totally different seat/bead design for example)

The rim has features to improve the benefits of RFT tyres, not reduce it's capability to use non-rft tyres.

Dave

 

[polak]

Well, Im definitely going to be changing to normal tyres come March. Cheers for all the information so far guys , its really useful! (never had run flats before, or fitted tyres on to rims! (although have done a good job a couple of times of getting them off ;-) ).


Now the only other question outstanding was if the suspension setup needed to be modified! (on facelift cars). Although I'm sure BMW would love to be able to charge for the pleasure of changing the setup!

 

[Zed_Steve]

Interesting to read that it is advisable to notify your insurance company if you decide to change to non rft tyres.

Noted.

 

[Batman]

Hey..

The Falkens went on the savo, first impression's very positive, car felt sharper with no crashing over bump's/potholes any more

And more importantly all 4 still on the wheels, haha.

Thanks for your help.

 

[Mr Whippy]

Ordered some FK452's from Camskill today at about 3pm, delivery tomorrow, all for £330!

Then another £80 fitting, but hey ho, Camskill are by far the cheapest to get these in the first place (that I found), and quick delivery too

Really looking forward to seeing what they are like on the backroad into work as the Bridgestones see me bottling it by about 50mph... my old Peugeot 306 GTi would push 80mph and still be stable! (thats where the oem Z4 tyres show how crap they are, on the rough stuff!)

Dave

 

[cj10jeeper]

Dave - you'll be amazed at the improvement

BTW - shop around for fitting unless oyu've paid already for an inclusive deal. My local guys does wheel tyre valve and balance at £10 per corner.

 

[mason storm]

It's been interesting reading this thread. I changed to Falkens a few months ago and now that I have also adjusted the pressure I run at to 30psi cold it feels far better and more stable on bumpy surfaces. All this talk of run flats though got me thinking that they must put extra strain on the car's suspension and may be the cause of my car being diagnosed with a broken rear coil spring? Makes you wonder as others seem to have also had this problem at low miles.

 

[srhutch]

Very ironic indeed - based on the the fact that the run-flats are shocking!

Going with the fact BMW told srhutch they wouldn't fit normals, kind of explains the negativity towards them from there point of view.

The only reason the dealer wont fit them due to the sue culture we are in now, they used to fit parts bought in by customers but now are to worried about being sued if something goes wrong.

 

[srhutch]

YES!! They'll be on the car this time tomo.

Also - has everyone notified there insurance companies when they've done the same?

IMO this is a must otherwise they may refuse to pay if you have an accident, my insurance company (esure) are happy for non run flats and no extra premium.