Reconsidered my position on Run Flats today.......
11-03-2006, 03:35 AM
#21
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Originally Posted by aybeesea' post='351639' date='Nov 2 2006, 02:25 PM
Toss an normal balanced coin 99 times and it lands heads. On the hundredth throw the probability of a the coin landing tails is atill 50%.
ABC
ABC
Your statement does not consider the fact that location and driving style may have a statistically significant impact on a person's likelihood of suffering a blowout.
11-03-2006, 03:39 AM
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Then there's the safety aspect. If you have a blow-out in a car not equipped with an electronic stability program, there's a good chance of losing control, especially at speed. The tyre bursts, you feel a wobble, over-correct and spin.
Invited to check this for myself, I watched four other journalists spin a BMW saloon at 80mph when a conventional rear tyre was burst, though all easily retained control on a burst run-flat. I tried the same thing with the car's Dynamic Stability Control (DSC) switched on and it kept everything shipshape. But of course it can't stop a conventional tyre from shredding. Put it this way: even on a car with DSC, I'd rather be on run-flats and I'd rather my loved ones were on them, too. So would the police, because there would be fewer motorway accidents to mop up and less tyre debris to collect.
Much has been written about the harder ride that run-flats give. This is partly due to the stiffer sidewalls they need in order to work when deflated and partly because the lower the tyre profile (ie, the shorter the sidewall), the better the run-flat will work. Bridgestone now makes two sizes of low-profile run-flats for the 5-series: 40-aspect 18in and 45-aspect 17in. We tried the new 18in tyre against the old one over a variety of surfaces and there was a distinct improvement in comfort.
Invited to check this for myself, I watched four other journalists spin a BMW saloon at 80mph when a conventional rear tyre was burst, though all easily retained control on a burst run-flat. I tried the same thing with the car's Dynamic Stability Control (DSC) switched on and it kept everything shipshape. But of course it can't stop a conventional tyre from shredding. Put it this way: even on a car with DSC, I'd rather be on run-flats and I'd rather my loved ones were on them, too. So would the police, because there would be fewer motorway accidents to mop up and less tyre debris to collect.
Much has been written about the harder ride that run-flats give. This is partly due to the stiffer sidewalls they need in order to work when deflated and partly because the lower the tyre profile (ie, the shorter the sidewall), the better the run-flat will work. Bridgestone now makes two sizes of low-profile run-flats for the 5-series: 40-aspect 18in and 45-aspect 17in. We tried the new 18in tyre against the old one over a variety of surfaces and there was a distinct improvement in comfort.
ABC
11-03-2006, 05:01 AM
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Originally Posted by aybeesea' post='351700' date='Nov 2 2006, 10:45 PM
...slow on your donut...
BTW contrary to what I previously thought, looking on this forum, it is not uncommon to get runflats repaired after a puncture and some subsequent uninflated driving.
ABC
BTW contrary to what I previously thought, looking on this forum, it is not uncommon to get runflats repaired after a puncture and some subsequent uninflated driving.
ABC
Repairs are probably possible to the same extent as with a non-RFT tyre (what's supposed to be most different is the sidewall, not the tread, and one can't repair sidewall damage on radials anyway), but there are a couple of horror stories about the tyre shredding off around the repair plug without too much warning. Quite how representative these are of reality, I don't know.
11-03-2006, 05:35 AM
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Originally Posted by dlevi67' post='351862' date='Nov 3 2006, 02:01 PM
Well, same speed - IIRC. The donut is rated at 80 km/h (50mph), and that's the max speed recommended on RFT too, I think.
Difference: the time taken to put the donut on (and the weather and road conditions in which you have to perform the swap).
ABC
11-03-2006, 05:58 AM
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But you can drive much, much further on the space saver and stay mobile if a replacement tyre is not at hand for a day or two. And, depending where it happens, that might easily be the case.
11-03-2006, 06:39 AM
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Originally Posted by olli_535d' post='351881' date='Nov 3 2006, 02:58 PM
But you can drive much, much further on the space saver and stay mobile if a replacement tyre is not at hand for a day or two. And, depending where it happens, that might easily be the case.
Did I say do without the space saver?
As for a space saver travelling much further... does that have some actual backed up numbers?
ABC
11-03-2006, 07:32 AM
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Originally Posted by aybeesea' post='351893' date='Nov 3 2006, 03:39 PM
I wouldn't want to drive very far after any puncture. I would just prefer to save time and be safe after the event. Of course in some remote territories, distances to an appropriate tyre centre may be a potential problem.
Did I say do without the space saver?
As for a space saver travelling much further... does that have some actual backed up numbers?
ABC
Did I say do without the space saver?
As for a space saver travelling much further... does that have some actual backed up numbers?
ABC
If anything, the bigger problem is that rubber perishes and it will perish more easily if not used frequently (even though it's not exposed to UV rays in the boot).
Also, whether anyone wants to drive 2000m @ 40-50 mph is kind of controversial...
11-03-2006, 08:43 AM
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Originally Posted by andymac' post='351298' date='Nov 2 2006, 01:29 AM
Did a 500 mile round trip at the weekend with my wife and 2 children in the car at motoway speeds. Just thinking that if I swapped for non run flats and then had a high speed blow out in this situation I would never forgive myself if anyone got injured.
A tyre very seldom explodes, so the driver has good time to react by slowing.
I remember having one pucture in 28 years of driving...
11-03-2006, 11:27 AM
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Originally Posted by Ricracing' post='351965' date='Nov 3 2006, 05:43 PM
At the speeds we are allowed to drive a high speed (max 140 km/h) puncture is not the end of the world.
A tyre very seldom explodes, so the driver has good time to react by slowing.
I remember having one pucture in 28 years of driving...
A tyre very seldom explodes, so the driver has good time to react by slowing.
I remember having one pucture in 28 years of driving...
The thrust of the article prompted by ABC earlier I can relate too.
Risk has been mentioned earlier in the thread and its nigh impossible to calculate here, we all assess risk in different ways applying differing influences - each will calculate their own position, the outcome decision is likely more influenced by how each individuals confidence is ensured by safety features, RFT's are a safety feature in my view.
Ricracing you've been fortunate for a good many years, long may it continue for your sake and all others too..........
11-03-2006, 12:06 PM
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Originally Posted by Nevermind' post='351831' date='Nov 3 2006, 07:41 AM
There seems to be something of a misconception here. One of the greatest advances in tyre technology was the introduction of tubeless tyres. This was done specifically to prevent blowouts. Tubeless tyres when punctured will not blowout. Damage that would cause a tubeless tyre to deflate so rapidly as to cause an accident would have a very similar effect on a run on flat tyre. Runflats offer no security advantage over a normal tubeless tyre, other than the fact that you are unlikely to get mugged when putting the spare on.
Forget the safety point of view, there isn't one!
Forget the safety point of view, there isn't one!
I'm with you bro, except RFTs don't come off the rim as quickly as standard tires. There is a BMW film on it, showing how the RFT car can continue to turn better with the flat. I'm sure at high speed the RFT will be more stable too when flat.
But I agree RFT's main attribute is your not changing a flat on the road.
CVT Benhogan
