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Post by racingteatray on Jun 24, 2019 15:13:06 GMT
Can anyone remind me what the recommended approach is when replacing tyres on cars with 4wd?
My mother has damaged one of the front runflat tyres (large sidewall bulge) on her Countryman, courtesy of a cratered bit of motorway tarmac, and needs to replace it.
As her's is an All4, I have it in mind that you need to replace the tyres like-for-like and in pairs (or worse all four) on 4wd vehicles? From what I understand, the All4 system is permanent but variable.
The car is a little over two years old and has done 21k miles, and she says that the tyres still have plenty of tread.
Not having huge amount of luck finding a clear answer on the web that I trust. |
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Post by Tim on Jun 24, 2019 15:19:32 GMT
The theory appears to be that you should replace the tyres on the same axle.
I'm not sure why that would actually make any difference and I wonder how I managed not to destroy many diffs on cars in the 90s when I was replacing tyres one at a time, even on the driven axle.
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Post by racingteatray on Jun 24, 2019 15:27:06 GMT
The theory appears to be that you should replace the tyres on the same axle. That's what I thought - so that the difference in rotation front to back is the same across the axle.
But just trying to get a straight answer, so that I can inform my mother accordingly. The village garage were simply going to fit one new matching Pirelli, and she's not thrilled at the idea that she might need two...
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Post by Tim on Jun 24, 2019 15:31:58 GMT
I suspect it might be an old wives tale (am I allowed to use that phrase?) put about by the tyre industry to recoup some sales lost by producing tyres that now last 50k miles!
I think I first heard it in relation to some Volvo estate, possibly the XC70 back when they first came out but I wonder if there's any actual evidence.
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Post by scouse on Jun 24, 2019 15:35:37 GMT
I didn't replace both sides when I got a flat on the XC60. Didn't notice any difference in the 10k miles I did after replacement.
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Post by racingteatray on Jun 24, 2019 15:44:09 GMT
Well, despite being in her 70s, my mother still does about 10k miles a year and is likely to keep this car for at least another 5-6yrs, so just want to make sure not storing up troubles for the future.
And I assume she can't claim compensation from the council or the Highways Agency, as the bulge was only pointed out to her yesterday by the chap washing her car. She then remembered hitting a pothole "with an almighty bang" at some point on the A1 on her way back to Suffolk from Yorkshire last weekend, but obviously can't remember exactly where.
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Post by Tim on Jun 24, 2019 15:52:49 GMT
And I assume she can't claim compensation from the council or the Highways Agency, as the bulge was only pointed out to her yesterday by the chap washing her car. She then remembered hitting a pothole "with an almighty bang" at some point on the A1 on her way back to Suffolk from Yorkshire last weekend, but obviously can't remember exactly where. It wouldn't matter anyway as you have to hit the hole at 3.26pm on the 3rd Wednesday of the month to even start the process. Plus it needs to have a nice, slightly faded, yellow circle spray painted around it, but not more recently than 7 days, for you to get to stage 2. Make sure your mum keeps the part worn tyre that's intact so if she does it again (probably an inevitability) she has that one to put on as part of a matching pair. |
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Post by johnc on Jun 24, 2019 16:06:00 GMT
Like Tim, I read about a Volvo estate many years ago where the diff went because a single tyre was replaced. Apparently it wasn't covered under warranty.
I am very much of the opinion that if you change one tyre on an axle you need to replace both (unless the other is very lightly worn)
I had one tyre replaced on the 435D because they had only done about 4,000 miles - the dealer had no problem replacing only one and made no comment at all about the fact it was only one tyre.
However at 21,000 miles I think I would just take an early bath and replace both.
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Post by racingteatray on Jun 24, 2019 16:15:04 GMT
Thanks all.
More from the village garage over the phone: "yes that is considered best practice and it is no doubt what Coopers (the local MINI dealership) would suggest, but we think you'll be fine just changing one because the other has plenty of tread"...
...although as yet what "plenty of tread" means has not been determined...
So she's going to order just one new matching Pirelli and get it fitted now, just to get her safely back on the road and get them to tell her what the exact tread on the other is, and let me know. Then if, when I learn the tread depth, I decide a second one is merited (pursuant to, among other things, opinion on here), she can order another one. The garage is only a couple of hundred metres up the street from her house.
What do we think? More than 5mm - leave it? Less than 5mm, change it? |
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Post by johnc on Jun 24, 2019 16:18:48 GMT
Yes, I think you're about right with your cut-off point.
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Post by Martin on Jun 24, 2019 19:25:09 GMT
It’s not a full time 4WD, so I’m pretty sure FWD rules apply when you get a puncture or rotate tyres.
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Post by ChrisM on Jun 24, 2019 19:53:31 GMT
Thanks all.
(snip)
What do we think? More than 5mm - leave it? Less than 5mm, change it? That's what I'd do - plus keep the "old" tyre if you did have to change 2, and store it out of direct sunlight |
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Post by Boxer6 on Jun 24, 2019 20:41:13 GMT
The 'rule' always bandied about on the Legacy forum was to replace both tyres on the same axle in event of a replacement being needed, always citing dire outcomes for the centre diff. I replaced a single tyre some 2k miles into ownership and ran it for about another 6-7K I think, with no issues arising. I'd suggest replacing one, with the caveat above, and she should be fine.
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Post by Roadsterstu on Jun 25, 2019 9:39:32 GMT
I didn't replace both sides when I got a flat on the XC60. Didn't notice any difference in the 10k miles I did after replacement. No, but the next owner will, when the diff starts whining because the bearings are shagged. That's what happened to me with the V60, although that FoMoCo diff is notorious for such failures (I know know!). The advice I gave my dad with the Superb 4x4 is to rotate the tyres so the whole set wears evenly and replace as a set. Not really that easy and not really spreading the cost. I think as a minimum change two on the same axle. |
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Post by Roadsterstu on Jun 25, 2019 9:42:25 GMT
It’s not a full time 4WD, so I’m pretty sure FWD rules apply when you get a puncture or rotate tyres. What do MINI recommend? I'd go with that rather than the local indy saying, "we think you're probably OK." |
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Post by racingteatray on Jun 25, 2019 9:46:03 GMT
Apparently the tyres still have 6mm tread. Seems almost improbable after 21k miles.
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Post by PG on Jun 25, 2019 9:52:16 GMT
At 21k miles, I'd be minded to replace both, keeping the undamaged worn tyre as a reserve.
Opinion on the web seems very unclear as to whether the MINI system is FWD plus power to the rear as needed or always all wheel drive. I think in the former cases, matching tyres on an axle are not so critical. But in a true AWD system, matched tyres on an axle are important for diff wear.
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Post by racingteatray on Jun 25, 2019 14:20:47 GMT
The reviews I read said the All4 system was permanent 4wd but variable allocation front/rear...not technically-enough minded to know whether that makes sense.
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Post by johnc on Jun 25, 2019 18:48:59 GMT
The reviews I read said the All4 system was permanent 4wd but variable allocation front/rear...not technically-enough minded to know whether that makes sense. It just means that all 4 wheels are driven all the time to some extent but when one starts to slip, power is redistributed to the others. I suppose in such an arrangement there must be quite an open diff most of the time but with a very quick reaction to redistribute the power to other wheels. |
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Post by ChrisM on Jun 25, 2019 19:14:49 GMT
6mm thread probably means no need to replace the other tyre on the same "axle"
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Post by Tim on Jul 2, 2019 14:57:31 GMT
I now have an answer for this and it's NOT good news.
My 320 - an xDrive - got serviced a couple of weeks ago and since then its had a slowly worsening stutter/misfire feeling.
Well it turns out that the £4k transfer box is now buggered and according to the video they've just sent me this will be because the front tyres are new (about a month old), showing 7.5mm of tread and the rear are around 25k miles old with 3mm of tread.
The electronics therefore think one of the wheels is slipping and try to sort it out resulting in the transfer box failure.
So the moral of the story - if you believe John Clark's - is that if you have to change 1 tyre then you'd better change all 4.
I will be seeking a second opinion.
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Post by johnc on Jul 2, 2019 15:03:04 GMT
So the moral of the story - if you believe John Clark's - is that if you have to change 1 tyre then you'd better change all 4. I will be seeking a second opinion. That is taking up-selling to a whole new level. Surely the solution is for tyre manufacturers to sell tyres with varying tyre tread depths based on the state of your other tyres so that you can get a matching set. |
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Post by Bob Sacamano v2.0 on Jul 2, 2019 15:22:34 GMT
I now have an answer for this and it's NOT good news. My 320 - an xDrive - got serviced a couple of weeks ago and since then its had a slowly worsening stutter/misfire feeling. Well it turns out that the £4k transfer box is now buggered and according to the video they've just sent me this will be because the front tyres are new (about a month old), showing 7.5mm of tread and the rear are around 25k miles old with 3mm of tread. The electronics therefore think one of the wheels is slipping and try to sort it out resulting in the transfer box failure. So the moral of the story - if you believe John Clark's - is that if you have to change 1 tyre then you'd better change all 4. I will be seeking a second opinion. And yet, in the BMW handbook, the section on X-Drive runs to one short paragraph and does not mention tyres or tyre wear at all. if it was such a big issue they would put a note in. I smell bullshit, particularly as you can't rotate the tyres with them being staggered. Apparently, while the dealer will tell you it's the transfer box on these sort of failures the culprit is usually the actuator motor which has a plastic gear within the housing that wears on one side. You can just turn it round 180 deg or buy a new one. I would have thought competent independents would know about this. I've also heard that BMW have reduced the price of the transfer box from £3k to £750 + VAT as an exchange item (they must be doing a few!) and it comes with the actuator. I also read somewhere that the X-Drive can cope with up to 1% difference in rolling circumferences on each wheel - so on a 19" wheel and 45 section tyre that would be about 585mm diameter, so up to 5-6mm tread difference per tyre. |
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Post by Tim on Jul 2, 2019 15:35:31 GMT
I find it impossible to believe that the system is so sensitive that it can detect a 4mm difference in the tyre depth between the front and rear. When I think of the piss poor roads I drive on every day, full of raised repair patches and mystery sunken bits I wonder how the diffs and transfer box cope with that?
The car was in for a service 2 weeks ago and while they told me the tread depths in their free video there was no mention of impending transfer box doom.
Even if its true they won't be getting the work.
Hopefully there's an easy temporary fix to allow me to shift the car on......
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Post by Tim on Jul 2, 2019 15:37:18 GMT
I now have an answer for this and it's NOT good news. My 320 - an xDrive - got serviced a couple of weeks ago and since then its had a slowly worsening stutter/misfire feeling. Well it turns out that the £4k transfer box is now buggered and according to the video they've just sent me this will be because the front tyres are new (about a month old), showing 7.5mm of tread and the rear are around 25k miles old with 3mm of tread. The electronics therefore think one of the wheels is slipping and try to sort it out resulting in the transfer box failure. So the moral of the story - if you believe John Clark's - is that if you have to change 1 tyre then you'd better change all 4. I will be seeking a second opinion. And yet, in the BMW handbook, the section on X-Drive runs to one short paragraph and does not mention tyres or tyre wear at all. if it was such a big issue they would put a note in. I smell bullshit, particularly as you can't rotate the tyres with them being staggered. Apparently, while the dealer will tell you it's the transfer box on these sort of failures the culprit is usually the actuator motor which has a plastic gear within the housing that wears on one side. You can just turn it round 180 deg or buy a new one. I would have thought competent independents would know about this. Thanks Bob, I'll be doing some research over the next few days to decide what to do. In the meantime I'll be Micraing to work so at least I'll have modern conveniences such as Apple CarPlay. |
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Post by Bob Sacamano v2.0 on Jul 2, 2019 15:51:26 GMT
And yet, in the BMW handbook, the section on X-Drive runs to one short paragraph and does not mention tyres or tyre wear at all. if it was such a big issue they would put a note in. I smell bullshit, particularly as you can't rotate the tyres with them being staggered. Apparently, while the dealer will tell you it's the transfer box on these sort of failures the culprit is usually the actuator motor which has a plastic gear within the housing that wears on one side. You can just turn it round 180 deg or buy a new one. I would have thought competent independents would know about this. Thanks Bob, I'll be doing some research over the next few days to decide what to do. In the meantime I'll be Micraing to work so at least I'll have modern conveniences such as Apple CarPlay. Don't know if this helps: axleaddict.com/auto-repair/BMW-Transfer-Case-Actuator-Problem-And-Fix |
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Post by ChrisM on Jul 2, 2019 17:08:44 GMT
I now have an answer for this and it's NOT good news. My 320 - an xDrive - got serviced a couple of weeks ago and since then its had a slowly worsening stutter/misfire feeling. There's your answer..... they "introduced" something when they worked on it |
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Post by Tim on Jul 3, 2019 9:26:52 GMT
I had a frustrating return trip to the dealer as by the time I got there all the useful service bods had, apparently, left the building and (I realise this is incredibly sexist) I think there's really little point in trying to have a meaningful discussion about transfer boxes and user advice with an orange female whose main aims in life appear to be to enhance the size of her lips and get as many sets of fake eyelashes on as possible.
I did point out that during the service the tyre tread depths were covered but no mention was made of potential transfer box issues as a result.
Anyway the invoice for them inspecting it says they pulled the transfer box supply fuse and the issue went away.
Bob, that link is for earlier versions of the X3 and X5, although I suspect the fundamentals are the same.
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Post by Roadsterstu on Jul 13, 2019 9:28:46 GMT
I now have an answer for this and it's NOT good news. My 320 - an xDrive - got serviced a couple of weeks ago and since then its had a slowly worsening stutter/misfire feeling. Well it turns out that the £4k transfer box is now buggered and according to the video they've just sent me this will be because the front tyres are new (about a month old), showing 7.5mm of tread and the rear are around 25k miles old with 3mm of tread. The electronics therefore think one of the wheels is slipping and try to sort it out resulting in the transfer box failure. So the moral of the story - if you believe John Clark's - is that if you have to change 1 tyre then you'd better change all 4. I will be seeking a second opinion. And yet, in the BMW handbook, the section on X-Drive runs to one short paragraph and does not mention tyres or tyre wear at all. if it was such a big issue they would put a note in. I smell bullshit, particularly as you can't rotate the tyres with them being staggered. Apparently, while the dealer will tell you it's the transfer box on these sort of failures the culprit is usually the actuator motor which has a plastic gear within the housing that wears on one side. You can just turn it round 180 deg or buy a new one. I would have thought competent independents would know about this. I've also heard that BMW have reduced the price of the transfer box from £3k to £750 + VAT as an exchange item (they must be doing a few!) and it comes with the actuator. I also read somewhere that the X-Drive can cope with up to 1% difference in rolling circumferences on each wheel - so on a 19" wheel and 45 section tyre that would be about 585mm diameter, so up to 5-6mm tread difference per tyre. This is exactly the issue. It's probably fine as the first or second owner and lowish miles but later owners will rely suffer - as I did with the V60. The diff repair specialist told me that manufacturers simply do not tell customers this. They say it is absolutely down to tyre wear. |
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Post by Roadsterstu on Jul 13, 2019 9:31:22 GMT
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