What IS the point of Run Flats?

laurence_p

my mums just had 2 17" conti run flats fitted £280 all in and another 45 quid to have the 2 wheels welded where they had cracked. i looked into this cracking on bmw wheels and a lot of people seem to think its the run flats causing the cracking because the sidewalls are so stiff. normally youd expect a wheel to crack on the inside edge (weakest point) but these had cracked in the middle. it was on watchdog a couple of years ago about bmw wheels cracking. i found out that the sensors they have fitted to their car (08 320d) only work when there is a drop of 30% suddenly and not when the tyre is going down slowly. so if you have these you must check them weekly and dont rely on the sensors telling you your tyres are losing air.

sunshinetours

SHIPSHAPE wrote: »

I agree, runflats could be useful but, I fear, more useless which is why I've never bought them.

I reckon there are quite a lot of gimmicks about tyres. eg Winter tyres? Give me a break! In the UK??

Better off with tyres that perform well in rain, be it mid July or late April.

Not again with the lack of comprehension about winter tyres (hint: it doesn't need to snow).... if you don't believe in them don't buy them - simple

Run flats have their place although I am not a fan. once they have been driven on after a puncture you have to get a new tyre as they cannot (in vast majority of cases) be repaired. SAying that I went with run flat on my winter tyres as I wouldn't have a suitable spare and most of my journeys are within 50 miles of home

sunshinetours

Gloomendoom wrote: »

A lot of manufacturers are deleting the spare even if conventional tyres are fitted as standard. All you will find in the boot is a tin of gunk and an air compressor.

I was pleasantly surprised to find that Mrs G's new car came with a full size spare wheel that matched the other alloys on the car.

Also a lot of performance rear wheel drive cars have staggered wheel set ups so front and rear are not same width and profile. A full size spare would only be suitable for one axle

if I was stuck somewhere on a run flat I woudl just call RAC/AA etc

vikingaero

BMWs on runflats were loosely "developed" for the American market which has a morbid fear of blowouts. The problem is that the current owners/drivers of BMWs are the development team for BMW with the appalling ride.

If you get a puncture on a runflat then it's a grey area about whether it can be repaired as there may be hidden damage to the sidewalls. Try buying a runflat on a Sunday from a tyre fitter and see whether your day will be ruined...

kaya

My friend has a corvette Z06 , the knowledge that if you get a puncture your tyre won't explode/shred/implode is very comforting when you are doing 180mph+

neilmcl

laurence_p wrote: »

i found out that the sensors they have fitted to their car (08 320d) only work when there is a drop of 30% suddenly and not when the tyre is going down slowly. so if you have these you must check them weekly and dont rely on the sensors telling you your tyres are losing air.

My tyre sensors have always worked correctly, besides you should always check your tyres manually rather than rely on tps systems to tell whether you have a slow puncture or not.

alanrowell

Apples2 wrote: »

On the balance of risk, I have been driving for 25 years, had many punctures but no motorway blowouts.

I've had a front wheel blowout at 70mph (ish) going downhill. The only effects were an increase in road noise & slightly heavier steering

harveybobbles

I've just spent the last 12 months with run flat tyres on my car and tpo be honest, they are the biggest waste of money ever.

I only had them fitted as I coulsn't get hold of any others at short notice.

The side walls are too hard (obviosuly) and as such, this increases the wear on the shoulders.

Going back to the OP's car - the 5 Series does have room to fit a full size spare wheel, so you could buy a 2nd hand wheel and tyre off ebay. Doesn't have to be the same style either.

Another thing to point out with the 5 Series, i you get one with the 19 inch Spider wheels, then you get a space saver, as they don't do runflats for 19 inch lol.

vikingaero

Runflats are very much a convenience item and as such you pay a lot more for them.

Here's two of my stories with punctures:

(1) Driving in Mrs V's Corsa to Eastbourne (55miles) and the OSR tyre deflates at 30mph. There's a petrol station 150 yards ahead so I pull in and change the tyre for the spare in 15 minutes and we're on our merry way.

(2) On holiday in Fort William about 600 miles from home. We're on our way to Iona via Lochaline/Fishnish. It's raining and I hit a water filled pothole. The runflat deflates and the warning message appears (530d Touring). With a 150+ miles to Iona and back to Fort William the decision is made and we turn back. We pay another £6 for the Corran Ferry. We ring around the tyre dealers and are told that they could order one in for delivery and fitting the next day or we should try the BMW dealer in Inverness 65 miles away. With the recommended driving distance already exceeded we return to our lodge and do a few local things. The next day we get the call that the tyre has arrived and is fitted. The day after we drive to Iona again - our costs increased by the £12 extra paid to Corran Ferry, £25 of diesel, and £250 for a new runflat. And my question for the salesman of my next car? Does it have a spare tyre!

colino

I think it was Dunlop (Denovo?) who set of on the idea of safety driven run-flats. However after all these decades and with beemers with tyres that are too harsh, difficult to balance properly and that cost an arm and a leg, I would say they will go the way of the Wankel engine. Good idea, but ultimately a waste of effort.