Star marked tyres X drive, what is the truth

[themule]

Hopefully I can get some advice. I have a 2011 e70 X5 40d Msport with the 20 inch wheel staggered setup and I need new tyres all round. There seems to be totally conflicting information out there if Star marked tyres are needed to avoid transfer box damage or not. Ideally I don't want to be paying over £1k for 4 Star marked runflats and would prefer non runflats for a slightly better ride, lower cost and more choice and just keep a pump and tyre goo in the car for emergencies. Do people have any thoughts?

[E-bmw]

So you have a few problems from my viewpoint but as to whether they are NEEDED or not others will be along to advise soon.

You bought a car that needs a set of £1000 tyres every couple of years & now you don't want to spend that, did you not think it would have been better to do this research before you bought the car then?

My understanding is that if you have un star marked tyres then you run the risk of transfer box damage & large bills. HOW MUCH RISK, I don't know, but as it is already a fairly well trodden path, do you really want to risk it?

WRT RFT/non-RFT, I would have thought if they do non-RFT tyres star rated, why not try them.

[Dynion Araf Uchaf]

I had to have a quick look to find out what exactly were 'star marked tyres'.

It appears to me to be branded or premium make tyres, with such caveats as , designed to work with your suspension as part of the BS that OEM's like to come up with.

It's probably true that the car might handle a bit better with star marked tyres but fundamentally it's about ensuring that you fit your tyres at a BMW dealer and not Kwikfit with cheap ling longs.

I think you will be fine to fit non star marked tyres so long as they match the dimensions of your current tyres. Also your car is out of warranty so you won't get any help from BMW anyway and you can't be certain that your car has only had star marked tyres fitted.

The only thing I am not sure about is what difference non run flats would make (other than improved ride quality). I suspect almost nothing to the actual drivetrain stresses and you could argue it might improve the stress levels on things like springs as they aren't as hard in terms of the sidewall.

[themule]

Thanks, I knew the cost of the OEM spec tyres and had always had the idea I would swap for non-runflats when the time came but didn't understand the star marked thing until yesterday. I had assumed that as long as you got matched premium tyres with the correct size and ratings that you were good to go with plenty of choice. I have run a 7 series and an M3 previously so am used to BMW running costs but buying tyres was never an issue and never seemed unduly expensive - albeit these had normal non flat tyres.
My question was about if people had experience using premium brand non star marked tyres on X drive vehicles with the staggered wheels. These are quite a bit cheaper - e.g. I have read good things about Vredstein Ultrac which are £250 each instead of £300 and have the same load rating. I can't see that there is a star marked non run-flat tyre available.

[E-bmw]

Dynion Araf Uchaf said:

I had to have a quick look to find out what exactly were 'star marked tyres'.

It's probably true that the car might handle a bit better with star marked tyres but fundamentally it's about ensuring that you fit your tyres at a BMW dealer and not Kwikfit with cheap ling longs.

Although you can buy *rated tyres from normal tyre outlets, so not sure if that is the idea.

Dynion Araf Uchaf said:

I think you will be fine to fit non star marked tyres so long as they match the dimensions of your current tyres. Also your car is out of warranty so you won't get any help from BMW anyway and you can't be certain that your car has only had star marked tyres fitted.

Warranty support isn't the issue though is it? It is about (possibly) risking a large bill as the warranty is out.

Dynion Araf Uchaf said:

The only thing I am not sure about is what difference non run flats would make (other than improved ride quality). I suspect almost nothing to the actual drivetrain stresses and you could argue it might improve the stress levels on things like springs as they aren't as hard in terms of the sidewall.

I will agree that you are likely 100% right there due to the additional compliance of the side wall, good point.

[AliMc99]

I've swapped to non-run flats on various BMW's (including a 335d X drive) and they've significantly improved the ride and handling (esp Michelins) and not caused any problems. I think you just need to have 4 matching tyres with similar tread depths (to avoid damaging the 4wd system)

[Easternlight]

There's a huge thread about this on here from earlier in the year.
The consensus was you need to run star tyres or the Xdrive will st it's self!

What a brilliant system.
Well done BMW.

Edit for thread link.
https://www.pistonheads.com/gassing/topic.asp?h=0&...

Edited by Easternlight on Friday 23 December 19:37

[themule]

Thanks, that is a helpful thread

[Earthdweller]

Easternlight said:

There's a huge thread about this on here from earlier in the year.
The consensus was you need to run star tyres or the Xdrive will st it's self!

What a brilliant system.
Well done BMW.

Edit for thread link.
https://www.pistonheads.com/gassing/topic.asp?h=0&...

Edited by Easternlight on Friday 23 December 19:37

I’m on my 3rd BMW with x drive, currently a F25 X3 owned for 7.5 years and 85k it’s not on runflats nor * marked

It hasn’t shat itself, nor did the F31 3 series that did 120k or the E84 X1 that did 60k for that matter

We also ran mainly X5’s but also 3/5 series X drives at work that weren’t on * marked tyres and some of them did 250k + miles in four years without stting themselves

Edited by Earthdweller on Saturday 24th December 19:11

[Easternlight]

Earthdweller said:

Easternlight said:

There's a huge thread about this on here from earlier in the year.
The consensus was you need to run star tyres or the Xdrive will st it's self!

What a brilliant system.
Well done BMW.

Edit for thread link.
https://www.pistonheads.com/gassing/topic.asp?h=0&...

Edited by Easternlight on Friday 23 December 19:37

I’m on my 3rd BMW with x drive, currently a F25 X3 owned for 7.5 years and 85k it’s not on runflats nor * marked

It hasn’t shat itself, nor did the F31 3 series that did 120k or the E84 X1 that did 60k for that matter

Glad to hear it.
That's how it should be, all this crap about the tyres being within 2% same diameter.

[themule]

Very good to know, thanks

[themule]

To update on this, I fitted Bridgestone Duelers all-round which are star marked run flat tyres. Black Circles was the best deal in the end. Not cheap but there was hardly any choice to fit the staggered setup, particularly at the back. I am actually delighted with the results, the ride is significantly more compliant and has gone a long way to solve the biggest issue I had with this car. There is also way less tyre noise. Whether this is down to the tyres being new or just a better tyre I am not sure but the difference is marked. I also have newly refurbished and diamond cut wheels so I need to steer clear of those curbs.

[kingofdbrits]

Easternlight said:

The consensus was you need to run star tyres or the Xdrive will st it's self!

Actually the complete opposite of this. In BMW world this has to be the biggest load of bks of internet hear-say, you know, like when a lie can get half-way round the world before the truth has got it's boots on, st sticks etc...

Just as the internet is full of horse st, it also has what the difference actually is. As if Michelin/Goodyear and the like would actually make a tyre deliberately so bad it'd wreck a diff, how could you even programme the manufacturing equipment of the tyres to make them so different in size from 1 tyre to the next??

Anyway, I did 140k miles with no star mark on my 335d, swapped my Bridgestone run-flats in my M340i for star marked MP4s, and I can't tell the difference as I won't be pushing the car anywhere near the limit on a public road where I might notice any difference in performance.

https://www.youtube.com/watch?v=COA630Juf_U

[ric p]

Had this exact issue with our latest F25 X3 M Sport with the staggered set up.

The ride was terrible on the runflats and the BMW star-ed tyres are expensive with little choice. We have used an independent exBMW chap in Yeovil for plus of 25 years. He is very well respected.

I wanted to improve the ride, it was Cardiffs demo so full M Sport with all the options with the notable exception of the sports suspension delete, very telling. Dave at Eden Motors’ view was that the bit that mattered was keeping the rolling radius similar, ie not running a new and a 2 mm tyre together. That is what upsets the system. The star bit is just marketing fluff in part.

I also ditched the run flat bit, which gave a much greater range of tyres at significantly better price. And improved the ride slightly. It is not really about not being able to afford to run the car but not spending money on unnecessary marketing driven rumour. Did ask my insurance company out of interest when I spoke to them about an other matter and they were completely disinterested. As long as legal was their only point.

However I then ditched the staggered wheels and bought a set of MSport non-staggered alloys, which were the standard non upgrade option. This change from runflats 19” to normal 18” is a revelation and the car now rides as a SUV should over urban uk roads rather than crashing around. And you can rotate the tyres to increase the life from them.

Ours is now at 110k and the transmission is still in one piece. We did get all the fluids replaced at 95k in the sealed for life system as Dave did suggest that does make a difference to the transmissions longevity.

My Porsche mates have this exact discussion re Porsche N marked tyres, anything else would mean instant death etc according to the interweb. Oddly they are all still fine despite running various tyres.

Edited by ric p on Monday 9th January 10:27

Edited by ric p on Monday 9th January 10:28

[Pica-Pica]

ric p said:

Had this exact issue with our latest F25 X3 M Sport with the staggered set up.

The ride was terrible on the runflats and the BMW star-ed tyres are expensive with little choice. We have used an independent exBMW chap in Yeovil for plus of 25 years. He is very well respected.

I wanted to improve the ride, it was Cardiffs demo so full M Sport with all the options with the notable exception of the sports suspension delete, very telling. Dave at Eden Motors view was that the bit that mattered was keeping the rolling radius similar, ie not running a new and a 2 m tyre together. That is what upsets the system. The star bit is just marketing fluff in part.

I also ditched the run flat bit, which gave a much greater range of tyres at significantly better price. And improved the ride slightly. It is not really about not being able to afford to run the car but not spending money on unnecessary marketing driven rumour. Did ask my insurance company out of interest when I spoke to them about an other matter and they were completely disinterested. As long as legal was their only point.

However I then ditched the staggered wheels and bought a set of MSport non-staggered alloys, which were the standard non upgrade option. This change from runflats 19” to normal 18” is a revaluation and the car now rides as a SUV should rather than crashing around. And you can rotate the tyres to increase the life from them.

Ours is now at 110k and the transmission is still in one piece. We did get all the fluids replaced at 95k in the sealed for life system as Dave did suggest that does make a difference to the transmissions longevity.

My Porsche mates have this exact discussion re Porsche N marked tyres, anything else would mean instant death etc according to the interweb. Oddly they are all still fine despite running various tyres.

The compound mix is the star mark * difference. This image is from Tyre Reviews’ Jon.

[JNW1]

Pica-Pica said:

he compound mix is the star mark * difference. This image is from Tyre Reviews’ Jon.

To me there are two separate issues here though; one is that star marked tyres might have a different compound from their non-star equivalent (which may result in different driving characteristics), the other is they're supposedly manufactured to tighter tolerances (which, it is rumoured, could have an effect on the X-drive system).

In terms of the first, the only time I've seen a difference in compound referred to specifically is in the context of tyres approved by the M-Division for M-cars. However, while those compound differences might be beneficial for, say, fast road work in the dry and/or on a track, my recollection was the non-star equivalents actually performed better in the sort of conditions most drivers are likely to encounter in the UK (like in the wet for instance). So for most drivers I think it's highly debatable that star marked compounds offer better performance for normal road use - quite the opposite from the evidence I've seen.

In terms of the second, I just struggle to believe the law and trading standards would allow manufacturers to sell tyres that differ significantly from their nominal, quoted, sizes. Of course a small level of tolerance will be accepted but it won't be massive, the manufacturers just wouldn't be allowed to get away with it. So if the argument is star marked tyres are essential for X-drive because they're made to closer tolerances - and the system can't cope with standard manufacturer tolerances - to me that's almost getting to a point of saying X-drive isn't fit for purpose. But I don't believe that and the number of drivers who've run high mileage on X-drive cars without a problem despite using non-star marked tyres suggests it's more robust than the scare stories would have you believe.

So while I'd never criticise people for using star marked tyres by the same token I think there's a lot of nonsense talked about the implications of not using them. Providing you fit tyres from a reputable manufacturer that are the correct size, speed rating, load rating, etc, for your vehicle I think you'll be fine.

[mekondelta]

To help answer the original question, it's recommended on many forums and also from my local BWM dealer that the difference in tread depth (not tyre size) between front and rear be no more than 3mm. On my F25 X3 I certainly felt the difference (shunt from the gearbox as if disengaging) from a standing start when I put a new set of rear tyres on and put old rears onto fronts. The fronts (IIRC) wear lower tread and so initially there was a 4+mm difference in tread depth but now that's settled down I feel much less shunt in the transmission as the difference between front and back has settled down. Just my experience but it bears out the advice I'd been given.

[JNW1]

mekondelta said:

To help answer the original question, it's recommended on many forums and also from my local BWM dealer that the difference in tread depth (not tyre size) between front and rear be no more than 3mm. On my F25 X3 I certainly felt the difference (shunt from the gearbox as if disengaging) from a standing start when I put a new set of rear tyres on and put old rears onto fronts. The fronts (IIRC) wear lower tread and so initially there was a 4+mm difference in tread depth but now that's settled down I feel much less shunt in the transmission as the difference between front and back has settled down. Just my experience but it bears out the advice I'd been given.

That makes perfect sense, the issue with X-drive is it struggles to cope with significant differences in rolling circumference front to rear and tyre wear obviously plays a part in that. However, the original question was about star marking and the situation you describe regarding wear obviously applies regardless of whether the tyres are star marked or not....

[mekondelta]

JNW1 said:

mekondelta said:

To help answer the original question, it's recommended on many forums and also from my local BWM dealer that the difference in tread depth (not tyre size) between front and rear be no more than 3mm. On my F25 X3 I certainly felt the difference (shunt from the gearbox as if disengaging) from a standing start when I put a new set of rear tyres on and put old rears onto fronts. The fronts (IIRC) wear lower tread and so initially there was a 4+mm difference in tread depth but now that's settled down I feel much less shunt in the transmission as the difference between front and back has settled down. Just my experience but it bears out the advice I'd been given.

That makes perfect sense, the issue with X-drive is it struggles to cope with significant differences in rolling circumference front to rear and tyre wear obviously plays a part in that. However, the original question was about star marking and the situation you describe regarding wear obviously applies regardless of whether the tyres are star marked or not....

Sorry yes, I was answering about transfer box damage in general and not about star-marking in relation to that. I just wanted to add the tread depth issue as I think that's the most likely cause of issues IMO.

[Pica-Pica]

mekondelta said:

JNW1 said:

mekondelta said:

To help answer the original question, it's recommended on many forums and also from my local BWM dealer that the difference in tread depth (not tyre size) between front and rear be no more than 3mm. On my F25 X3 I certainly felt the difference (shunt from the gearbox as if disengaging) from a standing start when I put a new set of rear tyres on and put old rears onto fronts. The fronts (IIRC) wear lower tread and so initially there was a 4+mm difference in tread depth but now that's settled down I feel much less shunt in the transmission as the difference between front and back has settled down. Just my experience but it bears out the advice I'd been given.

That makes perfect sense, the issue with X-drive is it struggles to cope with significant differences in rolling circumference front to rear and tyre wear obviously plays a part in that. However, the original question was about star marking and the situation you describe regarding wear obviously applies regardless of whether the tyres are star marked or not....

Sorry yes, I was answering about transfer box damage in general and not about star-marking in relation to that. I just wanted to add the tread depth issue as I think that's the most likely cause of issues IMO.

But tread depth itself is not a guide, surely? Front and rears on staggered already start with different RCs (rolling circumference), unless star marked vary from ETRTO measurements. With mine then a 8mm front tread depth and a 2mm rear gives a 1.6% difference in RC, and a 2mm front and an 8mm rear gives a 2.2% difference in RC (they start off at 0.3% difference). Besides, albeit short-term duration, when a tyre is run-flat (as they can be), the RCs are much different than 2.2%