12-22-2012, 07:36 AM | #1 |
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Winter tyres. Garage ordered no RFTs
As the title, went this morning to get my tyres changed over.
They dropped the ball, realised they ordered non RFTs. Not much of a choice really as I'm driving up to Edinburgh Monday. The ride is better for it actually. But where do I stand in terms of getting a puncture or something? Mobility kit? call the AA? Or just tempt fate and hope it doesn't happen. Not the best picture. Was quite limited with the rim and tyres because of the short notice. Think it looks like a US cop car in a video game.
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12-22-2012, 08:15 AM | #3 |
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I would have made them get the run-flats.
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12-22-2012, 08:30 AM | #4 |
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Interesting, dealer said they'd refuse to fit non-RFTs (summer or winter) to my car and also said if I chose to have non-RFTs fitted by someone else, it might affect my insurance given the car is 'set up' for RFTs. Never know with these people whether they're just stringing you along
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12-22-2012, 08:57 AM | #5 |
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If I wasn't pressed for time, I would've made them get the run flats. But to be honest, it's given me something to think about noticing the difference in ride and noise. I got a good price too so didn't want to be too arsey.
Googling about though, BMW do sell a mobility kit (compressor and slime). Why would they do that if they didn't let people use non rfts. Probably more so that they prefer you to use rfts so wont give you the option. I know as a customer we expect to be given the choice since we're paying so much but sometimes though not giving a customer the option makes life so much easier. 'setup' for rfts, thats something I've not heard before.
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12-22-2012, 09:28 AM | #6 | |
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But as the generations of cars and tyres has gone on, cars are certainly more workable with RFTs than at the beginning. Whether we can say that a model won't work, or can still be improved without RFTs these days, that is still open to debate. Particularly as BMW have lots of wheel options which change/compromise ride and handling of a car anyway. BMW make mobility kits as some models don't have RFTs. Also for the M-cars which have run without spare wheels (or RFTs) for quite a while. BMW never officially sanctioned changing from RFTs, even from the early days when even some wheel options were not RFT shod. Also reminded users we were possibly compromising emergency cover if caused by punctures on non run-flat tyres. Even used the threat of warranty being invalid. Many dealers were more enlightened and would still support the users who moved from RFTs, as my dealer did for me. Latest cars like the F10 and F30 are definitely more tuned and suited to RFTs, the F30 was the first BMW with RFTs I drove which I could not feel any negative RFT characteristics through the chassis and steering. I had the concerns when buying the F11 that I would be fighting RFTs again, but not so, neither the summer set, or more surprising the winter set, with tempertures already being down to -6C and the RFTs still working well. HighlandPete |
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12-22-2012, 09:54 AM | #7 |
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As always Pete, a fountain of information
I suppose I'm only using non run flats for a the winter months anyway. Re: CoolDude196 I got them from a company called 'selecta tyre'. http://www.selectatyre.co.uk Mate of a mate so I got a good discount, I think, because I didn't shop around so nothing to compare to apart from the price from BMW. TSW Mugello rims, Yokohama winter tyres, not sure which (the non rfts) . Filled it with nitrogen too. They had some nicer rims on display, I would've preferred straight spoke and maybe gun metal grey. But I'm happy, looks mean. £1200 all in.
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Last edited by Deyvy; 12-22-2012 at 10:00 AM.. |
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12-22-2012, 03:18 PM | #9 |
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X3's run-flats all the way and BMW do not like none run-flats fitted to cars designed for them, some insurance/warrantee issues from memory.
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12-22-2012, 03:26 PM | #10 |
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Er, nope, sorry - the 320ED definitely does not have run flats - and I have just done a quick configuration on BMW website on X3 sdrive18 and run flats are a cost option.
Non run flats only available on some of the basic models I think So I am right (too many wasted hours on BMW configurator..) |
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12-22-2012, 03:34 PM | #11 | |
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12-22-2012, 04:02 PM | #12 |
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Plus some markets don't have RFTs the same way as the UK specifications, F30 included.
What is in dispute... has been from when RFTs were first introduced, exactly what does BMW do to 'tune' for RFTs? Certainly was asked in the beginning and to a degree can still be asked today. Where we have options for RFT upgrades, for which tyres was the chassis set up? As suspension parts don't change with tyre options. So if you buy say an X3, which has RFTs fitted due to the wheel upgrade, removing them and fitting non RFTs is no more than returning the vehicle to base specification. Which is the 'safe' chassis? All the comments through the years on being dangerous, waiting for an accident to happen and scare stories was completely unfounded on BMW specification alone. Let alone when BMW/Bridgestone demo tested the 3G RFTs against 2nd generation and standard tyres on the same E60 chassis, to try and prove 3Gs were as good as non RFTs. So what was that all about if the chassis was designed and setup for RFTs? A lot of questions have been asked of BMW on this "tuned for RFTs" over the years and the official answer is never convincing. The unofficial view has been a bit different. Some track tests on the Z4 have shown running non run-flats, on the "designed for run-flats" chassis is the better handling car. HighlandPete |
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12-23-2012, 02:08 AM | #13 |
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My assumption has always been that the stiffer sidewalls of the RFTs means they can reduce the stiffness (compression/rebound?) of the suspension by a notch to compensate. That would then suggest that with non-RFTs fitted (on a car 'tuned' for RFTs) the overall suspension setup would be a tad too 'soft'.
Personally I am a wee bit skeptical. Consider a 320i SE for example. That comes on RFT-shod 17" 393's, yet you can spec it with 19" 439's on the configurator, also with RFTs. My guess is that the 19" wheels would give less compression and rebound than 17" ones, yet despite being so obsessive about the handling claims of their cars, I don't suppose for one minute that BMW alters the suspension settings in any way depending on what size wheels you go for. I could see how the adaptive suspension might compensate, but the stock setup no way. Also, I'd be surprised if the ED which has non-RFTs had a different suspension setup to say an equivalent SE, Modern etc., which does ride on RFTs. So for BMW to start claiming that fitting non-RFTs would affect your warranty, or insurance companies suggesting that somehow a non-RFT equipped car might be a higher risk - I think they're just milking it But then I'm looking at this from a layman's perspective and am happy for someone who knows a thing or two about suspension to put me right
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12-23-2012, 05:14 AM | #14 | |
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12-23-2012, 09:03 AM | #15 |
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My understanding is that all F30's come with runflats as standard. However, you can spec option Z58 from the factory for 16-inch wheels and 16-inch wheels only. Z58 is a no-cost option and it means non-runflat tires (instead of the stock runflats). FWIW, I specifically requested non-runflat winter tires for my 320i xDrive.
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12-23-2012, 12:15 PM | #16 | |
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All those same models/lines could have optional wheel sets on RFTs, up to 19" staggered specifications. All this on standard (non sport) suspension. What has been clear from BMW technical documentation, the standard wheel size/tyre for a model is the best compromise of all relevant criteria, which includes safety and roll comfort. Bigger wheels, (including RFTs, if the BMW statement applies across the range) means further compromises to some of the criteria, including noise and aqua-planing properties, (again from BMW data). So let's take our typical German F30 320d on standard suspension with the 7J x 16" rims with 205/60 R16 non run-flat tyres, we can't be much softer for suspension/tyre combination. Is any model on 17" or 18" fitted with non run-flats, less safe than the OEM 16" non run-flat tyre models? I know guys did suspension part checks for the E9* models to see if any components were changed with wheel sizing, when OEM fitments allowed for both non run-flat and run-flat tyres. Nothing was flagged up as changing. I suspect nothing changes for the F30/1 models either, only the damping/spring/ARB rates which change with models anyway, typically according to weight changes, and specific options (like the rear ARB with the panoramic sun roof option), but not particularly wheel/tyre influenced. Big subject, as suspension settings are all about compromises anyway. HighlandPete |
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12-24-2012, 11:29 AM | #17 |
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Historically Run flats caused a major ride comfort issue due to the following:
With suspension the rule is generally - the lighter the unsprung weight, the softer the suspension set up required. This typically baffles people as they look at the weight of the car being cushioned from shocks, but actually it is easier to understand the general mass of the car as being static and the wheels having to move up and down over bumps. If the wheel is heavy, it will tend to want to 'ramp' off bumps as it has a lot more energy in it. Hence the need for stiff spring rates to keep heavier wheels on the ground. The above is a double whammy for RF tyres as they are both stiffer in side wall AND heavier requiring heavy spring and damping rates = poor ride quality. My understanding is that the latest generation RFT's are not quite as stiff as they once were (it is now acceptable understanding that they are only required to drive a reduced distance flat, coupled with a history of consumer d feedback data). As they have less material in the sidewall they are lighter, so moving back towards more standard tyre set ups. Not quite there yet though. Another thing to add to the mix, is that modern allow wheels (at least the BMW ones) are flow formed rather than gravity die cast, which means they are significantly lighter. So much so that the larger alloys no longer have the weight penalty they used to have. Hence the same CO2 for 19" as the 18" and 17" variants. So a 19" rim yes does weigh more than an 18 for example, but has lighter in comparison tyres fitted to it. Especially so in RF format. |
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12-24-2012, 11:49 AM | #18 | |
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