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Messages - Spandex

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General X5 Forum (E70) / Re: A star tyres , myth or fact
« on: Today at 05:12:08 PM »
If you can get a photo of the fronts next to the rears on a flat surface for comparison, that might help others considering them too.

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General X5 Forum (E70) / Re: A star tyres , myth or fact
« on: April 18, 2018, 11:53:04 PM »
There are numerous threads across various forums where people discuss uneven wear front to back on these cars. It’s not uncommon.

Regardless, it’s a hypothetical question. How the treads end up different isn’t really relevant. Do you know the answer?


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General X5 Forum (E70) / Re: A star tyres , myth or fact
« on: April 18, 2018, 11:05:00 PM »
I’m not talking about wearing unevenly across the tread of a single tyre. I’m talking about the fact that the front pair will wear at a different rate to the rear pair. Nothing to do with alignment.

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General X5 Forum (E70) / Re: Tow weight chassis plate
« on: April 18, 2018, 08:15:07 AM »
Isn’t your max towing weight a legal definition, rather than a technical one? What I mean is, if the registration documentation says you can only tow 2500kgs, then that’s all you’re allowed to tow legally, and what’s written in a manual, or chassis plate, or what you’re technically capable of towing, is completely irrelevant.


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General X5 Forum (E70) / Re: A star tyres , myth or fact
« on: April 18, 2018, 08:03:14 AM »
I think it’s generally agreed, even amongst those who only fit star rated tyres, that if you fit 4 tyres that are the same tread pattern and the same rolling radius (actual, not calculated from the sidewall size stamp) then you’ll be fine.

The debate here is more about how far you can move from “exactly the same size” without causing damage. Clearly there is some tolerance because even star rated tyres won’t stay the same size throughout their life and these cars don’t wear tyres evenly front to back.

Kkx5, you clearly have a fair bit of info on this, so maybe you can help out - if I have a complete set of star rated tyres fitted new and over the miles the fronts wear differently to the rears, at what point would I have to bin them and buy a new set? What tread depth difference is dangerous, assuming the tyres started off the same depth and same overall radius.


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General X5 Forum (E70) / Re: A star tyres , myth or fact
« on: April 17, 2018, 11:19:50 PM »
Err... what are?

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General X5 Forum (E70) / Re: A star tyres , myth or fact
« on: April 17, 2018, 08:49:57 PM »
Thats what my pictures shows. Same size approved vs non.
But it doesn’t matter if the non approved tyres are a different size to the approved ones. What matters is if a non approved staggered set of identical make/model are different in size. It would also be interesting to see a side by side staggered set of star marked tyres too, to see if they really are identical.

In theory, if BMW really are specifying rolling radius as part of the star mark program, then approved tyres from different manufacturers should be identical sizes too.

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General X5 Forum (E70) / Re: A star tyres , myth or fact
« on: April 17, 2018, 10:51:22 AM »
Ahh, ok. I still think the person who posted that in the PH thread thought it means the size/weight would be the same for different sized tyres in a staggered set up.

I think your last paragraph is broadly correct, in that star marked will be guaranteed to start off within tolerance, whereas non-star marked means there is a risk. I'd just love to find out how big that risk really is, because sticking to star marked tyres seriously limits your choice, and as others have noted recently, prevents you from moving to non-runflats (with all the benefits that brings).

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General X5 Forum (E70) / Re: A star tyres , myth or fact
« on: April 17, 2018, 08:25:46 AM »
For example:

A response from Dunlop on another forum gavce the info that the star marked tyres are made to a specific rolling weight AND radius (which works out the same no matter what size is on the sidewall) so not only the transfer box 'feels' the same weight and resistance from both axles but also the TPMS which works from the ABS sensors isn't fooled either by the increase in rotating mass or the difference in rolling radius.
I read that thread before. That quote is a bit ambiguous, because clearly a 275 and a 315 tyre of the same design, radius and sidewall height are not going to be the same weight. Which makes me believe they are actually referring to quality control for an individual tyre size - i.e all of the 315/35/20 tyres of a particular design will be rigorously checked to ensure they’re the same size and weight. Basically, it makes me think either the spokesperson from Dunlop misunderstood the question, or the response has been taken to mean something that wasn’t intended.

If you look on page 3 there is a post from someone who claims to work for a tyre manufacturer that kind of backs up that theory. They say that the star rating is a quality control stamp only, and there is no reason why you shouldn’t fit non-star marked tyres, as long as you ensure they meet the tolerances for your vehicle.

<edit>Just to add to the top paragraph, obviously 10J and 12J wheels will also be different weights, so there is no point whatsoever trying to get the tyres the same weight, only to stick them on different weight wheels. Something about that Dunlop response doesn't add up.

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General X5 Forum (E70) / Re: A star tyres , myth or fact
« on: April 16, 2018, 09:48:00 AM »
So if BMW recommends that and it's 1.1% out then that is okay,but how far it can be out before it causes probs I haven't found as yet.
Yeah, the problem is, BMW can happily 'recommend' something that is miles away from the actual threshold because a) they just need to cover their arses and b) they don't mind being ultra-cautious because they're not the ones paying for the tyres. Whilst I'm interested in their recommendations, I'm also aware that they won't ever give us the full story.

All the handbook says is to fit star rated tyres as  these have been recommended by the manufacturer.
The trouble is, I'm pretty sure BMW say that in every handbook for all of their cars regardless of which wheels are driven. All the other 'luxury' marques say the same about their own manufacturer-rated tyres too.


Simplest way to test  the theory is to put whatever tyres on you want, and let us know how you get on...
That's the method I'm hoping to avoid by finding out out if anyone has some actual facts regarding requirements/specs for star marked tyres, or actual tolerances for the x5 drivetrain. And even if that information simply isn't available, I think it's important to be clear when people ask for advice. Simply telling everyone who asks that they have to buy star-marked or risk their transfer box exploding isn't helpful.

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General X5 Forum (E70) / Re: A star tyres , myth or fact
« on: April 16, 2018, 12:39:10 AM »
Just to be clear, I’m not really questioning the idea that tyres of differing diameters could damage a transfer box or diff. I have no doubt that’s the case. What I would really like to know is how different they need to be before it’s an issue - because it’s entirely possible that there are plenty of tyres out there that aren’t star marked but are well within that tolerance. It’s also entirely possible that excessive wear on one axle could push a set of star marked tyres dangerously out of tolerance.

That’s why I get a bit annoyed by people repeating generalisations and confusing correlation with causation. It tricks people into buying things they don’t need to buy and, worse, it gives people a false sense of security.

12
Problems / Re: Help please - Can't get in my car
« on: April 14, 2018, 06:47:56 PM »
I take it the alternator is visible from underside then? I'll have a look tomorrow. :o
That’s what I’ve read, but I have no personal experience. Have a look at this video, although it’s so blurry and dark it’s a bit useless...

https://youtu.be/veh1eGTWZ7M

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Problems / Re: Help please - Can't get in my car
« on: April 14, 2018, 05:27:35 PM »
I’ve read that you can get to the alternator positive terminal from underneath... If so, you should be able to get an external battery hooked up (-ve connected to a chassis ground) and get enough juice into the system for the fob to unlock it.

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General X5 Forum (E70) / Re: A star tyres , myth or fact
« on: April 14, 2018, 09:49:39 AM »
Just one comment to above pictures: As long as some of You will question star marked tyres, i will have a job:)
The knowledge is there for many years. Buy cheap tyres, pay high diff/gear/transfer box bills. If you can not afford to pay £900 for set tyres on high tech 4x4 BMW, go and buy a ford fiesta....
The reason some of us will continue to question star marked tyres is because people like you post unhelpful nonsense like this. There was absolutely zero useful information in that post, but let’s break it down so you can address it properly.

1. You haven’t commented on the pictures above. We still don’t know what they’re supposed to show.
2. Cost is irrelevant. There are expensive tyres which are non-star rated. There are (relatively) cheap star rated tyres.
3. if the knowledge is ‘there’, then please help us out and post it here. It would be really helpful. What isn’t helpful is repeating anecdotal evidence that has huge logical holes in it.

As I’ve said, star marks on your tyres doesn’t mean they’re within tolerance for their whole lifespan, so it simply can’t be true that star marked tyres never cause issues. Or, the tolerance is much bigger than is being stated here, in which case it would be useful to know what it really was so people could make informed decisions when buying tyres.

When people repeat a mantra like “buy star rated and you’ll be fine”, it just makes me think they don’t really have any in depth knowledge at all.

15
General X5 Forum (E70) / Re: A star tyres , myth or fact
« on: April 13, 2018, 10:16:25 PM »
So how can star rated tyres never cause problems, when it’s perfectly possible (likely, even) that star rated tyres will wear unevenly to the point where they’re well past the circumference difference that apparently has caused problems for members on here?

Star rated tyres don’t magically stay the same size across both axles throughout their life. If 3-4mm tread depth difference is enough to cause a catastrophic failure of the transfer box, how are any e70s still on the road, given that all of them - even those with star rated tyres - will spend some of their life in that state?

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