Runflat tyre question

pinball wizard said:
Yeah. Imagine you're on holiday somewhere and you damage a tyre on a pothole, and all you can get is a replacement regular non-runflat tyre (correct size and spec) to get you home again, only to find out your month old christmas present to yourself now has it's motorplan cancelled.
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Exactly.

I had this conversation with BMW before regarding changing exhausts on my bike and how that relates to warranty and the seemingly obvious thing was that they would no longer cover my exhaust under warranty (since it would no longer be there).

The only caveat was that if I were to go beyond the section in the pipes that include the servo-controlled valve (like replacing with full headers) they would need to do the work and load the related maps for me to retain engine related warranty claims.

At no time whatsoever would changing my exhaust affect any other part of warranty coverage.
 
The only BMW model I have direct knowledge of is the first generation X3, and they’re prone to transfer case damage if you run the wrong tyres for long enough, so that might be the basis for insisting on specific tyres. Even so, you’re welcome to fit whatever make you like, as long as they’re approved by BMW (same thing for oil - it has to meet the manufacturers standard).
 
Colin62 said:
The only BMW model I have direct knowledge of is the first generation X3, and they’re prone to transfer case damage if you run the wrong tyres for long enough, so that might be the basis for insisting on specific tyres. Even so, you’re welcome to fit whatever make you like, as long as they’re approved by BMW (same thing for oil - it has to meet the manufacturers standard).
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How does running the wrong tyres affect the transfer case?
 
Neuk_ said:
How does running the wrong tyres affect the transfer case?
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Unless they’re exactly the same circumference, the axles rotate at different speed, and the mechanism that provides the four wheel drive tries to compensate and it wears out. Was about R40k to redo the transfer case a few years back.

It also means that replacing less than four tyres at a time is risky. And the tyres are expensive. It’s stuff like that that pushes up the running costs unexpectedly.
 
Colin62 said:
Unless they’re exactly the same circumference, the axles rotate at different speed, and the mechanism that provides the four wheel drive tries to compensate and it wears out. Was about R40k to redo the transfer case a few years back.

It also means that replacing less than four tyres at a time is risky. And the tyres are expensive. It’s stuff like that that pushes up the running costs unexpectedly.
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That describes a very common issue when running different size tyres but not an issue from running the wrong tyres, which I still don't understand.
 
Neuk_ said:
That describes a very common issue when running different size tyres but not an issue from running the wrong tyres, which I still don't understand.
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Wrong sized tyres perhaps, put on bigger tyres, more strain on the transfer case as the ratios is out then. only thing that makes sense to me...
 
Neuk_ said:
That describes a very common issue when running different size tyres but not an issue from running the wrong tyres, which I still don't understand.
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I was told that the BMW recommended tyres are all within a gnat’s ball hair of each other sizewise, and are therefore OK. Other, cheaper tyres might be the exact same size but also might not be. But the guys who tell you this are usually selling tyres so now o is five that is I don’t know. I do know that the salesman didn’t drive a BMW himself though.

My engine went before the transfer case so I never got to find out for myself. :)
 
Colin62 said:
I was told that the BMW recommended tyres are all within a gnat’s ball hair of each other sizewise, and are therefore OK. Other, cheaper tyres might be the exact same size but also might not be. But the guys who tell you this are usually selling tyres so now o is five that is I don’t know. I do know that the salesman didn’t drive a BMW himself though.

My engine went before the transfer case so I never got to find out for myself. :)
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They fault code the moment you put the wrong size tyres on them for the very reason, so a transfer case issue should never occur in the first place unless someone manually overrides it.

But still different size/profile are a very different thing to different type of tyre.

If they wanted to reject a warranty claim or motorplan claim because the tyre was the wrong size and not according to spec then I fully agree they should reject it.

But not when going from runflat to normal all other things being the same.
 
The run-flat tyres on my Merc should be inflated to about 370kpa, based on the car's specs. That is almost double the pressure compared to any other car I have owned.

I assumed that the suspension is tuned to that specific tyre and that is why other tyres should not be fitted.
 
Messugga said:
Sure. I'll find the email from BMW when I threw me toys about how shitty the tires are that came on the car. They told me I simply need to deal.
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Nothing wrong if you replace tyres with a different brand.
 
deesef said:
The run-flat tyres on my Merc should be inflated to about 370kpa, based on the car's specs. That is almost double the pressure compared to any other car I have owned.

I assumed that the suspension is tuned to that specific tyre and that is why other tyres should not be fitted.
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Has got nothing to do with the suspension and purely the tire technology.

Your tire isn’t a member of your suspension balance, whether they run at 1 bar or 4 bar your suspension still works the same.

That tyres change the feedback to your car and therefore makes for a harsher or softer ride, that is however true but still doesn’t change the efficacy of the suspension itself.
 
Flarsiep said:
Wrong sized tyres perhaps, put on bigger tyres, more strain on the transfer case as the ratios is out then. only thing that makes sense to me...
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The transfer case would be on of your worries along with your clutch, gearbox, diff's, CV's, etc. You would have to either have a very weak drive train or go to a massive size wheel/tyre combination to have an issue. I know it's not exactly the same but a friend with a Jeep Wrangler (TJ) is running 33" tyres on non-OEM steel wheels at the moment and the only real issue he has had was having to change the rear diff ratio as 6th gear became useless.
 
Colin62 said:
I was told that the BMW recommended tyres are all within a gnat’s ball hair of each other sizewise, and are therefore OK. Other, cheaper tyres might be the exact same size but also might not be. But the guys who tell you this are usually selling tyres so now o is five that is I don’t know. I do know that the salesman didn’t drive a BMW himself though.

My engine went before the transfer case so I never got to find out for myself. :)
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Sounds like classic salesman talk to me, were you also told that the engine going is perfectly normal and all BMW's do that? What happened to the engine?
 
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