Run Flat Tyres
Discussion
Yes, I think so. Ran my 535d with run flats for a year, low speed ride is very poor and you can feel the suspension struggle to cope with the extra unsprung weight. Just switched into a B5, firmer suspension, bigger wheels but with Pilot Sport 2 tyres and the ride is in a different league.
There's a space under the boot for a spacesaver tyre (which you have to buy separately if the car came on runflats).
Steve
There's a space under the boot for a spacesaver tyre (which you have to buy separately if the car came on runflats).
Steve
They're absolutely rubbish.
1. Cost almost double a proper tyre
2. Most tyre places won't repair them, some even have difficulty replacing them
3. Ride and grip are compromised
Get tyre weld / space saver and use proper tyres. It was the best thing I ever did to my car, throwing away those useless run-flats.
1. Cost almost double a proper tyre
2. Most tyre places won't repair them, some even have difficulty replacing them
3. Ride and grip are compromised
Get tyre weld / space saver and use proper tyres. It was the best thing I ever did to my car, throwing away those useless run-flats.
535d said:
What are your thoughts on these? Does the ride quality suffer enough in your book to nullify any advantage they have with punctures?
Neighbour of mine bought a nice new mini. Got a puncture. Took in to be repaired and needed a new tyre cause they couldn't repair it..... £85. Had he been running normal tyres....£10.
chilli said:
What are your thoughts on these? Does the ride quality suffer enough in your book to nullify any advantage they have with punctures?
Neighbour of mine bought a nice new mini. Got a puncture. Took in to be repaired and needed a new tyre cause they couldn't repair it..... £85. Had he been running normal tyres....£10.
Exactly what happened to me, twice. The annoying thing is, that it's actually possible to repair a runflat, it's just that almost all garages refuse to do it.
I have just got a MINI fitted with them , im not sure if the ride os harsh because of the 17inch wheels or because of the RF tyres , i suspect the later
For example in the morning or if the car has been standing while at work when you drive off it feels almost like the wheels are square for the first few km's like they have a flat spot !! any one else noticed this
For example in the morning or if the car has been standing while at work when you drive off it feels almost like the wheels are square for the first few km's like they have a flat spot !! any one else noticed this
I think the answer is basically safety.
In the event of a puncture, the run flat's additional sidewall strength will allow the tyre to provide reasonable grip, and not fail for quite some mileage (I think it was 50 miles or so).
With a normal tyre, the sidewall can overheat quite quickly, and cause the carcass to fail with potentially serious consequences.
Because it is not readily apparent when one has a puncture in a run flat, BMW fit a tyre pressure monitoring system to alert the driver to a drop in pressure. The idea of course is that one doesn't drive around for weeks on a flat tyre unaware, as the run flat only lasts for so long. (This is also why garages worry about repairing them - if it has been run flat for a long time, it will be weakened and hence dangerous to repair in case it later fails. For a normal tyre, the evidence of running flat is clear to see (eg, stress marks in the sidewall) and one would be advised to change it in such circumstances. Otherwise there is no reason why a run flat can't be repaired - indeed BMW did repair one of my tyres.)
In terms of its affect on ride, there are two issues. First, run flats have a reinforced, and hence very stiff, sidewall. This has the attendant negative effective on ride. The second more insidious issue is unsprung weight due to the tyre's additional mass. In my 535, you could feel the dampers struggling to damp oscillations in the front wheels as a slight vibration through the steering wheel when driving over short, sharp ridges and such like.
The latter issue seems to have arisen because the 5 series was not designed from the ground up for run flats. However, press reports suggest the new 3 series has been, and therefore the suspension copes better with the additional unsprung mass - allegedly (I've not driven one) the new 3 series generally does not suffer the same ride issues as the 5 with runflats.
All that said, I still prefer a normal tyre, less unsprung mass (better for handling too), and a spacesaver in the boot.
Steve
In the event of a puncture, the run flat's additional sidewall strength will allow the tyre to provide reasonable grip, and not fail for quite some mileage (I think it was 50 miles or so).
With a normal tyre, the sidewall can overheat quite quickly, and cause the carcass to fail with potentially serious consequences.
Because it is not readily apparent when one has a puncture in a run flat, BMW fit a tyre pressure monitoring system to alert the driver to a drop in pressure. The idea of course is that one doesn't drive around for weeks on a flat tyre unaware, as the run flat only lasts for so long. (This is also why garages worry about repairing them - if it has been run flat for a long time, it will be weakened and hence dangerous to repair in case it later fails. For a normal tyre, the evidence of running flat is clear to see (eg, stress marks in the sidewall) and one would be advised to change it in such circumstances. Otherwise there is no reason why a run flat can't be repaired - indeed BMW did repair one of my tyres.)
In terms of its affect on ride, there are two issues. First, run flats have a reinforced, and hence very stiff, sidewall. This has the attendant negative effective on ride. The second more insidious issue is unsprung weight due to the tyre's additional mass. In my 535, you could feel the dampers struggling to damp oscillations in the front wheels as a slight vibration through the steering wheel when driving over short, sharp ridges and such like.
The latter issue seems to have arisen because the 5 series was not designed from the ground up for run flats. However, press reports suggest the new 3 series has been, and therefore the suspension copes better with the additional unsprung mass - allegedly (I've not driven one) the new 3 series generally does not suffer the same ride issues as the 5 with runflats.
All that said, I still prefer a normal tyre, less unsprung mass (better for handling too), and a spacesaver in the boot.
Steve
I did read somewhere, that a Mini on run-flat 17s had a worse ride than the same car on traditional 18s. Sems pretty damning for the former design.
The 535d is my first experience of run-flats and the ride is indeed pretty unforgiving.
>> Edited by 535d on Saturday 28th January 08:37
The 535d is my first experience of run-flats and the ride is indeed pretty unforgiving.
>> Edited by 535d on Saturday 28th January 08:37
I think they are a bag of sh1te as well... cant say that I have noticed poor grip though...
I had one go on the 120 and changed it for another runflat.. why? I hear you ask... because I'd rather a little light go on telling my wife to drive home slowly rather than have her try and sort the tyre out with tyre weld on the side of the road.
I had one go on the 120 and changed it for another runflat.. why? I hear you ask... because I'd rather a little light go on telling my wife to drive home slowly rather than have her try and sort the tyre out with tyre weld on the side of the road.
doctorpepper said:
I had one go on the 120 and changed it for another runflat.. why? I hear you ask... because I'd rather a little light go on telling my wife to drive home slowly rather than have her try and sort the tyre out with tyre weld on the side of the road.
I have tryed tyre weld stuff on a couple of occasions ,, the crap never works
535d said:
I have yet to hear a good word about these tyres. Does anybody therefore have a clue why a sensible company like BMW insist on fitting them?
But they don't fit them to the flagship models like the M3 / M5 do they? I suspect it's got something to do with thousands of people going back to their BMW dealers to get new tyres, and having the unpleasant news that one single 195*16 tyre costs £160 (a price one rather embarrased BMW mechanic quoted me). That must be a nice little earner.
You can fit normal tyres to the wheels that have been sullied with run flats. Just don't listen to any bull
t from a garage. They'll swear blind that you can't put proper tyres on the wheels, and it's utter rubbish. I even had one place saying that they couldn't put proper tyres as it would affect the tyre pressure sensors, which are operated via the brakes and not even located on the wheel / tyre. MINI's have the option of runflats or proper tyres with a can of weld, they all come with the same wheels.535d said:Got rid of them (Goodyear EMT) off my Corvette and it's a great leap forward. So far as I can make out BMW are having all the same problems with their Bridgstones. Gives me the perfect excuse to keep my old Beemers on the road and save up for a Z06!
The 535d is my first experience of run-flats and the ride is indeed pretty unforgiving.
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