New 08' 550i Run Flat Question
12-02-2007, 08:27 AM
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Originally Posted by Rock14' post='501309' date='Nov 30 2007, 09:42 PM
Got the 550i and it came with run flats.
Do they all come with run flats? The car has a spare and I asked the fleet manager if anything would happen if I went to regular tires. He told me the bushings on the car would go out quicker because of the softer ride. Seems like crap to me.
What do you guys think?
Thanks,
Rock
Do they all come with run flats? The car has a spare and I asked the fleet manager if anything would happen if I went to regular tires. He told me the bushings on the car would go out quicker because of the softer ride. Seems like crap to me.
What do you guys think?
Thanks,
Rock
In the UK 550i M sport comes with 19" rims and Standard tyres (this is a very good package IMO).
I have a 545i sport and removed the run flat tyres as soon as I picked up the car - the ride is greatly improved.
But I have had more tramlining - the reason - standard tyres have a wider foot print (and more grip) so can be more sensitive to camber changes and tramlining.
Most of the idiot dealers know nothing of supension or tyres - they just want your money and will tell you anything.
If you check the bushes 'part numbers' I am sure you will find a 550i with 19" rims will have the same bushes as a 550i with 18" rims and run flats.
I fitted Goodyear F1's and have quite alot of tramlining I am now going to try Contis or PS2's.
I want a car thay will do fast smooth runs on bad pavement (we only have bad pavement in the UK) and the chioice of the standard tyre and finding the right pressure is the answer.
J
12-02-2007, 08:46 AM
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Originally Posted by ima545tit!' post='501808' date='Dec 2 2007, 12:27 PM
But I have had more tramlining - the reason - standard tyres have a wider foot print (and more grip) so can be more sensitive to camber changes and tramlining.
What probably contributes to the increase in tramlining is the softer sidewall of a standard tire. The softer sidewall might allow the tire to conform (angularly) more ruts in a road where a stiffer runflat sidewall might cause the tire to track across the imperfections better.
That said, I remember hearing many runflat owners complaining about tramlining and claiming that once they switched to conventional/standard tires, the tramlining was decreased. Maybe tramlining is more a function of the tread design or some other feature of a particular tire?
12-02-2007, 03:18 PM
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Thanks for all the information!
I thought I had non run flats when I bought the car initally after doing alot of research on this forum. Just wanted to double check and looks like I was right.
I would like to think the people who work for BMW would have some knowledge of the product their selling.
I thought I had non run flats when I bought the car initally after doing alot of research on this forum. Just wanted to double check and looks like I was right.
I would like to think the people who work for BMW would have some knowledge of the product their selling.
12-02-2007, 04:26 PM
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Originally Posted by pukka' post='501396' date='Dec 1 2007, 02:41 AM
I have, the ride is noticeably softer - but to my liking. I think many people here switched to non-run flats and liked it.
Cons against run flats:
1 - Cost Agreed..
2 - They wear out faster I'm not sure why this would be true, unless is is a characteristic of the individual tire.
3 - Stiffer and more noisy ride. Agreed.
4 - Increased weight Agreed
5 - Higher rolling resistance which worsen's fuel economy Why would the rolling resistance be higher? I thought is was mostly a function of sidewall flex. more flex creates more resistance. I would think that extra stiff tires would have less rolling resistance.
Cons against run flats:
1 - Cost Agreed..
2 - They wear out faster I'm not sure why this would be true, unless is is a characteristic of the individual tire.
3 - Stiffer and more noisy ride. Agreed.
4 - Increased weight Agreed
5 - Higher rolling resistance which worsen's fuel economy Why would the rolling resistance be higher? I thought is was mostly a function of sidewall flex. more flex creates more resistance. I would think that extra stiff tires would have less rolling resistance.
12-02-2007, 04:27 PM
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Originally Posted by Rock14' post='501928' date='Dec 2 2007, 07:18 PM
I would like to think the people who work for BMW would have some knowledge of the product their selling.
12-02-2007, 04:31 PM
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Originally Posted by Rudy' post='501817' date='Dec 2 2007, 12:46 PM
I'm not an expert at tire dynamics but it seems to me that the "foot prints" should be the same between standard tires and runflat tires given the same tire size.
What probably contributes to the increase in tramlining is the softer sidewall of a standard tire. The softer sidewall might allow the tire to conform (angularly) more ruts in a road where a stiffer runflat sidewall might cause the tire to track across the imperfections better.
That said, I remember hearing many runflat owners complaining about tramlining and claiming that once they switched to conventional/standard tires, the tramlining was decreased. Maybe tramlining is more a function of the tread design or some other feature of a particular tire?
What probably contributes to the increase in tramlining is the softer sidewall of a standard tire. The softer sidewall might allow the tire to conform (angularly) more ruts in a road where a stiffer runflat sidewall might cause the tire to track across the imperfections better.
That said, I remember hearing many runflat owners complaining about tramlining and claiming that once they switched to conventional/standard tires, the tramlining was decreased. Maybe tramlining is more a function of the tread design or some other feature of a particular tire?
- Negative camber (BMWs have a lot, and cars with ZSP have more.)
- Wide tires
- Stiff sidewalls.
- Tread designs with circimferential grooves.
12-02-2007, 04:35 PM
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