Sorry! tyre Q

I've just changed to non-runflats (all be it I don't have 108s), ordered through Black Circles and fitted by Protyres in Bristol, no problems whatsoever.
 
Yeah, I've done lots of tracks/driving with non runflat tires on the OEM rims with ZERO problems. About the only problem you should encounter is the tire guy having a super tough time getting the runflats off the rim.
 
As per a previous thread, I was going to have non-runflats fitted on my 108s. My insurance company (MoreThan) said that was OK as long as I could get a letter from BMW saying it was an acceptable setup. I thought that would be no problem because (correct me if I'm wrong) the M is sold by BMW with 108s and non-runflats. However, BMW customer services said that while they considered it safe they would not issue a letter to that effect because it is not a standard setup. Their argument was that the M has a different suspension setup and is therefore not the same in spite of the fact it's the same wheels with the same tyres. In the end I have thrown it all into the "too difficult" basket and I'll probably go for the Pirelli RFT or something when the time comes. BMW said they have about 20 calls a week asking for confirmation that non-runflats is an acceptable setup.
 
Medium Dave said:
As per a previous thread, I was going to have non-runflats fitted on my 108s. My insurance company (MoreThan) said that was OK as long as I could get a letter from BMW saying it was an acceptable setup. I thought that would be no problem because (correct me if I'm wrong) the M is sold by BMW with 108s and non-runflats. However, BMW customer services said that while they considered it safe they would not issue a letter to that effect because it is not a standard setup. Their argument was that the M has a different suspension setup and is therefore not the same in spite of the fact it's the same wheels with the same tyres. In the end I have thrown it all into the "too difficult" basket and I'll probably go for the Pirelli RFT or something when the time comes. BMW said they have about 20 calls a week asking for confirmation that non-runflats is an acceptable setup.
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Change insurance companies (unless the premium rate is so advantageous) - most do not consider it an issue at all
 
You can understand their reluctance though - look at the old Ford Explorer tyre issue in the US, can you imagine the product liability lawsuits flying about every time some dumbass ran his Zed off the road while wearing non-RFTs? :roll:
 
2 dogs!!!!!

Like Gannet said, Michelin PS2 ZPs. So far, ride great. Quiet. Not as stiff as OEM. (of course, I had no problems with the OEMs!)
 
Just picked my car up a couple hours ago (53 plate 2.5) – I’ve had Goodyear Eagle F1 Asymmetrics fitted. Have only just driven to buy a can of Tyreweld and then back to work, but what a difference! Bumps are felt but without the previous jolt. The real revelation, even at slow speeds, is the steering – this could be the releasing agent, time will tell.

Real test will be once they’ve scrubbed in a bit (not sure how long that takes these days) and I give it a push on the b-roads.
 
PawnSacrifice said:
Just picked my car up a couple hours ago (53 plate 2.5) – I’ve had Goodyear Eagle F1 Asymmetrics fitted. Have only just driven to buy a can of Tyreweld and then back to work, but what a difference! Bumps are felt but without the previous jolt. The real revelation, even at slow speeds, is the steering – this could be the releasing agent, time will tell.

Real test will be once they’ve scrubbed in a bit (not sure how long that takes these days) and I give it a push on the b-roads.
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Welcome to the forum PawnSacrifice :D
 
Late reply to the insurance part of the thread. I agree, change your insurance company- getting a letter from BMW is complete bolleaux. I checked if they would have an issue and their face wasn't bothered
 
cj10jeeper said:
Hi 2 dogs. I too am on the non RFT's. Fitted by my local garage NE of Birmingam

Just for the record all that is spouted about not fitting standard tyres on RFT rims is rubbish. I posted a thread sometime back and the only difference is that the rim has an extra lip inwards of the normal seating position. This is purely to stop a deflated RFT wandering around the rim and falling off. It has no effect whatsoever on fitting a normal tyre.

I've had them on my 108's for a few months now and managed 350 miles around Wales 10 days ago and we def got above 50mph on the mountain roads :)
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That is basically it, the nature of a rim designed for RFT is an additional feature, not an exclusive feature. You can mount any tyre you like, perfectly fine, with no added dangers or concerns. What would be an issue is adding an RFT tyre to a non-rft wheel because the tyre could then wander and it may not be so much use to 'run on flat' at higher speeds/distances.

The BMW manual even states (maybe not owners, but technical guides) that you can use non-RFT tyres. It says in certain circumstances when you can't find an RFT, but the fact they say you *can* in the day and age of legal issues etc, suggests that even BMW know it's perfectly fine.


So much junk spread about so many things, like suspension being set up for them too, but it's all just junk from people who have little real idea.


Ie, springs in series, Z4 wheel rate at rim, maybe 25kN/m, effective wheel rate ~ 20kN/m with a 100kN/m tyre rate (fairly soft say a 16" rim with tall side wall tyre), go to a 200kN/m tyre (twice as stiff), and the effective wheel rate moves to 22.2kN/m, a whopping 10% increase in wheel rate... going from 80kg driver and no luggage and little fuel to 80kg driver AND passenger, luggage and fuel, has more effect on the kinematics of the suspension and tyre/suspension deflections than DOUBLING the tyre rate!
Even the stiffest highly inflated RFT won't be much over 300kN/m, so nothing to worry about, considering a normal 18" low-profile sports tyre will be in the 200,000kN/m range already anyway! (remember an RFT *stays* stiff when deflated, it's not hugely stiffer in normal operating conditions)


All said and done, RFT's on the Z4 ruin straight line stability (tyre compressions and resulting rebounds feel to thrust the car laterally randomly, especially at the rear with all that camber), ride comfort, add extra expense, and probably help towards snapping those rear springs.

Dumping them is the best thing you could do. BMW M realised that, which should tell you something :)

The downsides of non-RFT's are literally that, you can't 'run on flat'

Dave
 
Did mine a year ago, best thing I ever did. Had mine done at Tyres Northampton in ,ahem,Northampton :D No issues at all with them or the Goodyear's I've fitted.I celebrated the positive effect on the car by treating it to a track day ay Donnington. :D :D
 
Just to add, I have non RF on my 108,s for a year now no problem,

But i think you are already there :D
 
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