E90 Tyres.

We've just bought a 2009 320D SE Saloon fitted with Bridgestone Potenza 225/45R17 91V run flat tyres.
On indifferent surfaces the ride is pretty grim to downright scary
depending on the speed and conditions, with constant sideways jitters, bangs and thumps and tramlining. The three year old Octavia, which it replaced, took such surfaces in its stride, albeit noisily.
The conventional wisdom seems to be to dump the run flats and fit 'normal' tyres. The local BMW service centre sees no mechanical disadvantage in so doing and says there are no warranty implications.
I favour the Continental Sport Contact 3 of the same size on which Kwik Fit are currently doing an offer with an on line price of 102.90GBP.
Please, any comments.
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Alan White
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BMW on their latest models seem to be moving away from their traditional strut suspension. Probably to try and make these abortions act like proper tyres.
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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On Thu, 22 Apr 2010 09:34:43 +0100, Alan

Frankly, it sounds like the 3 series is just too sporty for you. You're not an old retired bloke are you? 8-O
I've got a 2008 325D M Sport (bigger wheels and tyres and lower stiffer suspension than yours) and I have to say that the handling and body control is superb. However, it's no comfy armchair. The seats are hard and the car bucks like a bronco if, and it's a big if, the council haven't bothered keeping the roads in even fair order. Having said that, I like the handling to be got from the stiffness of the run-flat sidewalls (as well as the safety benefits).
However, I've spent most of my life in sporty cars and I know what comes with that territory. Knowing the roads you're likely to be experiencing, changing tyres won't make the vast improvement you're after..I'd change your car manufacturer.
I'm 10 miles west of Glasgow and my last car did very well on Conti Sport Contact 2 tyres - good in the Scottish wet 'n' dry and long lasting.
All IMHO of course.
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On Thu, 22 Apr 2010 17:28:25 +0100, Zathras

Sixty skittering mph max in the BMW where the Octavia (2.0TD PDI 140bhp) would cruise solidly at eighty is hardly sporty. This is on the A82 north of Tyndrum.

Well, if the tyre change doesn't work, that's the next option.

Thanks.
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On Thu, 22 Apr 2010 18:35:27 +0100, Alan

Actually it is. You've just chosen the wrong sort of 'sporty' for the roads you drive on. It's fairly easy to buy a sporty car and find it doesn't go fast on certain road surfaces (says he speaking from experience!).
I would suggest that the Beemer is a moderate to good road sporty car. However, for the roads you're talking about, you need sporty with some off-road capability! Off the top of my head, an Imprezza or Evo would do a lot better.
While an extreme example, the difference in 'sporty' would be like F1 compared to a rally car. Both are sporty but wouldn't work on each others territory against native competition.

..and a few more too!
Have you any idea what's actually causing the 'skittering'? I'm puzzled because mine is always regarded as a bit more extreme than the SE and I haven't experienced..what...er..A82?..hang on a minute..all I've said so far might be irrelevant..
How long have you had the BMW? I remember now that I found mine an unnerving experience (particularly when overtaking) on roads like the A82 for a wee while after I bought it. The problem was migrating from long term nose heavy front wheel drive to a more potent, differently balanced rear wheel drive. The feedback through the BMW steering wheel is a bit dull and the completely different feel on power meant that I could end up weaving mid way through a high speed overtake! This issue completely vanished after two or three months (I guess) as my brain servos recalibrated to BMW rear wheel drive. Thinking back, I could have described it as skittish. The car and me are completely solid now and I haven't changed tyres or anything else.
I wouldn't get too excited about tyre pressures. I was running my tyres at 28PSI (instead of 40 odd!) for a while and when I pumped them up to the correct values, there wasn't a huge difference - again, the stiffened run-flat sidewalls interfering with things..
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A couple of things are quite clear (I have a 335d and my son has a 335i, both with run-flats.) 1) When brand-new, runflat tires are not terribly susceptible to tram-lining. 2) It doesn't take much run-in to make them bad 3) The low-profile tires accentuate the badness. 4) The original run-flats had problems with quality control; some were replaced under warranty (in the US) when they wore un-evenly and caused handling like you complain about. 5) Newer tires are "better" - my son noticed the difference between my 2010 tires and his 2007. How much better is debatable.
If you can put 205/50 tires on the rims you have, I'd go that route.
I haven't driven the A82 since 2000 when I was last in Scotland, so I can't say if it's as bad as some of the roads here in the US. ;-)
FloydR
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On Fri, 23 Apr 2010 07:41:08 -0700, "Floyd Rogers"

It's pretty bad!
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they wore out, I replaced the Z rated RE 050a run-flats on my Z4 with non run flat Goodyear Eagle F1 GS-D3 and frankly noticed little difference in the ride.
While I've no experience with the Conti 3 tires, I went thru a set of the original SportContacts and a replacement set of SportContact 2 tires on my E46. While they handle very well, the ride was nothing to write home about nor was the tread wear.
Have you experimented with tire pressures yet?
Tom
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wrote:

Started at the 'door plate' values of 2.3/2.8 and dug out a recommendation of 2.2/2.6 which made a slight improvement. One of my regular bends is a long, sweeping left-hander which the Octavia negotiated on rails at 70 mph. The BMW requires constant correction and feels uncomfortable. To say that we're disappointed is an understatement. I read elsewhere that an owner was ashamed to take passengers when running on run flats. Here's hoping!
Having said all that, it's a very nice car and on a smooth surface is a lovely drive, but...
The Contis are being fitted tomorrow. I'll report back.
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The Contis were fitted yesterday afternoon and today we did a sixty mile round trip to part run them in.
Tramlining has been eliminated, the bangs and crashes generated by the RFTs have been replaced by muffled thuds and the vehicle can now be relied on to go where it's pointed without constant corrections. All in all, it appears to be a successful solution.
Thanks to all for your comments.
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Just the difference I'd expect between proper tyres and run flats.
The very first car I drove with run flats was a '74 Rover P6 with Dunlop Denova wheels and tyres. Those spoilt the ride too. With no benefits to the handling.
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On Sat, 24 Apr 2010 17:46:45 +0100, "Dave Plowman (News)"

Do you remember Groundhog crossplies, and the goofy cartoon advertising campaign for them? I think that that was the last gasp of the crossply as a road tyre. Who the hell was it who made them? Dunlop? Damned if I can remember.
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On Sat, 24 Apr 2010 13:51:13 +0100, Alan
Just curious, how are you going to deal with punctures/blow outs? Spray can or spare wheel or..?
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On Sun, 25 Apr 2010 12:25:42 +0100, Zathras

See:-
http://www.care4car.com/productdisplay/productid/231/Continental_Compressor_and_Tyre_Sealant_Kit.html
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On Sun, 25 Apr 2010 13:52:10 +0100, Alan

Fair enough. The only thing that puts me off those is that a colleague of mine suffered a massive rear tyre blow out on a roundabout after using that kind of repair. He went off the roundabout backwards and did a lot of damage to his car..
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A spare tire in the trunk is always a good idea.
Thing about tire failures is that just about every real tire failure that I have had was something that wouldn't have been handled by run-flats. Almost all of them involved some kind of sidewall damage from road debris. --scott
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On 25 Apr 2010 11:03:29 -0400, snipped-for-privacy@panix.com (Scott Dorsey) wrote:

Yeah but a spare is going to take up a lot of space in a 3 series. Plus, I'm lead to believe that BMW will not export the boot/trunk floor to the UK that allows the spare to fit under the floor.
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