View Full Version : Run flat tyres, programmable iDrives and so on and so-forth . .

Loose rivets
10th Jul 2016, 16:42
I feel dazed. I'd greatly appreciate some technological input.

There seems to be so much to learn about modern cars, but having walked onto the drive of a dealer's private home and seen a BMW 635d, I had one of those feelings I had when I was a teenager and came home with kit like an Oldsmobile 88 - with Sport mode.

(Over 6ltr into a Hydromatic in Sports mode was something rather special in the late 50's. It would have been so nice had the car been equipped with a mechanism to stop it!)

Anyway, I knew that if I bought this car I'd lick it clean every morning. Yes, unashamedly robbed from Clarkson.

Diesel? I've never been too sure, but half an hour later being thrust in the back by a force every bit as great as the E500 Sport used to deliver, I was convinced the write-ups were true. Fifteen-hundred rpm and the darn thing was on its way, with 80% thrust at 1700 rpm.

All very nice, but now I'm finding a lot of 'However's'.

Carrying a pump in the stead of a spare wheel. 'Oh, it's okay, you've got some green stuff to mess the inside of the tyre with'. A real run-flat will set you back nearly 400 quid, and they don't repair them. Oh, and they insist on changing the valve. Since that talks to the system, the charge for that is . . . lots, despite being able to whip the cap off and put it on the new valve.

All this is of no use if, like shots I'm seeing on t'net, the darn tyre splits along the wall of the tyre - miles away from a phone signal. No, got to get a wheel . . . and jack . . . and even a wrench, and do weightlifting for a hobby.

Now I find the darn thing is two insurance groups up from the 630i. How did that happen? Have the underwriters discovered these bus engines develop more power than a Saturn II rocket? Bavaria should have kept quiet about that.

Then there's the iDrive. It seems one needs a CIC. Huh!? Back to the Not the nine o'clock news sketch of 'would you like woofers? Would you like a bag over your head?' I empathise with Mel Smith's poor customer and his request to see a . . . a radiogram.

The iDrive is learnable but now I find, with a sequence comparable to Los Alamos's main safe that even Richard Feynman couldn't break in to,* there's a different level of complexity I can reach - if I want to. Of course, I want to. Hoorah! Now I can make lights come on slowly, doors close silently, boots open mysteriously and my mirrors fold in . . . all with my key fob. Oh, wait. I haven't got a key fob. The car senses my hormones and turns on in a way that's a welcome surprise to my Hippocampus' enrandyment circuits. They haven't measured a response like that for longer than I'd like to admit to and by now my new love affair is even causing long-forgotten physiological changes to take place, and it seems, all for the better. My hair is gaining a higher proportion of black, I've stopped making an involuntary slurping noise when I eat soup, and my Y-Fronts have become as uncomfortable in a comfy chair as they are when I ride a 1000cc dirt bike, which I now feel compelled to do. And all done by spending some of the kids' inheritance.

Back to searching for a wheel.

*Breaking into safes was one of the professor's hobbies. When his boss asked him to help get into their new (huge) safe - to regain access to the world's greatest secrets (true) Dick Feynman failed to crack the code. A man from the safe company was flown to the top secret base to help. It seems he walked in, gave a few twists and the door opened. Clearly they could not have trusted the phone for such a code, but it wasn't a very secret code and indeed was one that lots of people knew. Lots of people that had purchased from the Acme safe co, because no one, or not many customers, bothered to re-set the default combination. From 'Surely you're joking Mr Feynman'. A great read.

Allan Lupton
10th Jul 2016, 17:21
Yes I suffer from one of those, a 320d in my case, and so much of the stuff in these cars is there because they can, not because anyone wants them to. Run-flat is the next step down the road to the unacceptable after the "spacesaver" as both assume you have your puncture within 50 km. of a tyre shop that is open and has a suitable size/make in stock. At least the spacesaver will get you there after a tyre-shredding incident!
We have lights that turn on if it gets dark and wipers that turn on if it rains - should someone who cannot be trusted to notice dark or rain be driving a car? Now what would really be a boon would be automatic headlamp dipping.
Some things, such as stop-start, can be switched off, but some have to be switched off each time you use the car.
Ergonomics play second fiddle to unwanted stuff, such as a huge arm-rest/junk stowage between the front seats that is so high that gear-changing and hand-brake pulling are compromised.

Gertrude the Wombat
10th Jul 2016, 17:32
After getting a puncture on a dirt road tens of miles from the nearest garage (ie, somewhat further than the get-you-home half-arsed spare was good for) I'm never again going to knowingly get into a car which doesn't have a full spec spare wheel.

10th Jul 2016, 17:55
The problem is that some cars no longer have space for a full-sized wheel and tyre.

10th Jul 2016, 17:57

Last two cars I got for SWMBO had these. The space saved in the wheel well is used up by a spacer to lift the wheel up so the boot floor remains flat. "Costsaver" would be more accurate.

50 miles available on one of these is absolutely no bloody use whatsoever when one visits Scotland regularly - it won't get you to the nearest garage in a lot of the country, or even to the nearest place where there's mobile phone signal.

First job for both cars was to buy a second hand full size spare with a good tyre a well-spent 25 - 30 for peace of mind.

10th Jul 2016, 18:03
I drive down to Bordeaux once or twice a year. I stick with my Passat Estate that still has a full size compatible spare wheel.
However, I would like to change to something like an Audi or BMW but cannot face the possibility of getting stuck somwhere with even a simple puncture (no spare or anywhere nearby to get a tyre change). The Audi guy said a lot of people just put another wheel in the boot! So I suppose that is one solution. This will obviously reduce the capacity for Bordeaux purchases.

10th Jul 2016, 18:12
I didn't want a 520D, I wanted a 530 (No D), but I was overruled by Mrs I and the Heir. It was made very clear to me that Mrs I was NEVER, EVER, going to jack up a car and change a spare tyre while she was driving. I also ended up taking the BMW "biscuit" option (The boot well is recessed to take it). Run flats, I always hated the lumpy, twitchy things, but I'm now on my 2nd set.

Why? one Winters night on the A26 somewhere between Dijon and Reims, I got the "flat tyre" indicator. It was raining heavily, very little traffic on the road, and probably around 25 Km to the nearest Aire with some limited service. I've now been "saved" around three times.

I carried on, drove steadily home, crossing on the ferry and didn't even get wet. The mechanic in my local tyre place showed me the 2" nail which had done the business, it was still in the tyre.

I was not about to buy another car with run flats for the Mrs just so I could have tubes, so the "boy racer" days are over. :{


10th Jul 2016, 18:20
Now what would really be a boon would be automatic headlamp dipping.

I had this on my Audi A6 - I think I'd had it for two days before I deactivated it as it was fairly useless. Far too slow in reacting to oncoming headlights and didn't dip at all when coming up behind a car. That was 4 years ago - maybe they are better nowadays.

10th Jul 2016, 18:33
This is what worries me about run flat tyres:
"Once a run flat tyre suffers a puncture, you can't keep driving on it forever usually you will be able to drive at c. 30 mph for another 50 miles plenty of time to get to your nearest garage. The exact range depends on variables like your driving speed, load of your vehicle and driving conditions."
I am sure this can be extended a bit but Bordeaux to my home is 600 miles.

10th Jul 2016, 18:33
Why? one Winters night on the A8 somewhere between Dijon and Reims, I got the "flat tyre" indicator.

Did your satnav not also tell you that you were on the wrong autoroute? ;)

10th Jul 2016, 18:41
Oh alright A26 then, it just seems like the A8 goes on for ever. :ok:

Gertrude the Wombat
10th Jul 2016, 19:11
The problem is that some cars no longer have space for a full-sized wheel and tyre.
In which case I am not the customer those cars are designed for.

Gertrude the Wombat
10th Jul 2016, 19:12
usually you will be able to drive at c. 30 mph for another 50 miles plenty of time to get to your nearest garage
Not in even the not-so-wilds of BC it ain't.

10th Jul 2016, 20:04
I've said this before on PPRuNe, so apologies to those that have read it before.

The whole idea behind getting rid of the full size spare and the use of run-flats and space savers is to save weight.

This in turn improves the cars power to weight ratio.

Further, this 'improves' the cars noxious emissions and reduces taxes.

All noble in their way, but if only the stupid makers would leave the normal sized well in the boot so that THE CUSTOMER could buy a full size spare and have somewhere to put it.

Some have pointed out the paucity of tyre shops in the wilds of Scotland, the problem in countries such as South Africa and Australia is multiplied many times.

10th Jul 2016, 20:28
Problem with buying a spare wheel for some cars (the BMW 330/335) for example, is that they have different sized tyres on the front compared to the rear.

In my experience, a run flat tyre certainly gets you to the nearest garage........where the car might remain for a week until they can source another run flat tyre of the correct size.

My 330 now runs on non-run flat tyres. I carry a tyre repair kit and a pump.
I did notice the difference in handling, the car feels slightly less planted than it did with the run flats. But a small price to pay. The tyres now fitted were considerably cheaper in any case, albeit of equally good quality.

Loose rivets
11th Jul 2016, 00:08
It was made very clear to me that Mrs I was NEVER, EVER, going to jack up a car and change a spare tyre while she was driving.

You beast! To even suggest such a thing.:}

First thing when I get a car - always used - I run all the wheel nuts off and on and have a bash at driving on the space-saver. The Mercedes one wasn't too bad, though I'd have hated Texas distances at 50mph.

The little 318ti has one under the boot/hatchback. It is lowered by a thingy inside. Slightly rusty with the weather, but quite serviceable. It's the diameter that's critical, get it wrong and the ABS and other calculations will cause the system to have a fit.

The boot on the 6 series is voluminous and it seems one can put a full sized wheel in there if you can accept a bump. Or a bermp, if you're in France.

Tomorrow's the day. I've a feeling he'll start looking for another punter if I don't commit soon.

I was walking along the lonely and windswept beach this evening, thinking I must be quite mad. I can't afford the car, but then, the prostate specialist that saved my bacon (is that what prostates are made of :confused:) showed me a booklet at our first meeting. It had a graph, or two in fact, one of which was life expectancy after brachytherapy, and one was just due to old age. The point they crossed was just about this week, so it seems I perhaps should have a fling or three. Mind you, the A12, on which I only used the BMW lane, seems to be covered in yellow cameras now. Do you suppose BMWs are exempt?

11th Jul 2016, 02:36
Definitely mixed feelings about 'run flat' tires. About 20 years ago, I was driving across Monarch pass at night (US 50 in Colorado, across the Continental Divide - about 11,000 ft.). Although it was August, it was snowing - as I came around a corner there had just been a rockfall and there was a canon ball sized rock right in the middle of the lane. Large enough that I was sure it would do damage if I ran over it so I swerved, just catching the edge of it with the left front tire. It opened up the sidewall like a can opener - it was flat before I was even sure I'd hit the rock :mad:. At least there was a pull off within a few hundred yards so I could get clear and change the tire - wearing t-shirt and shorts - in the wet snow in relative safety. All wheel drive Mitsubishi Eclipse - due to the all wheel drive the spare was full diameter, but little wider than a bike tire and hard as a rock. It was ~100 miles to my destination, part of it through the Arkansas river canon (aka "The Royal Gorge". It was raining, and the bicycle left front had minimal traction - I literally had to continually remind myself to slow WAY down for the right hand curves since the car didn't want to turn right.
I currently have a BMW 328xi (all wheel drive) with run-flats. Three years ago I was driving across south eastern Idaho late at night in early February when I got that dreaded 'low tire pressure' light. It had recently snowed, and the OAT was around -20 C. Knowing I had run-flats I continued on to the next rest stop without slowing from my 75 mph cruise speed. At the rest stop I checked the tire pressure - ~20 psi so I knew it was a slow leak so I continued ~50 miles to a truck stop in Utah (Snowville - one of the most fittingly named towns ever). I filled the tire up to about 40 psi, before continuing on to Layton where I was planning to spend the night. In the morning I checked the tire pressure and it was single-digit, so I went to a tire store to get the tire replaced.

Now, there are aspects of the run flats I don't like, they cost more (but not 400 quid - I recently replaced all four on the BMW with wonderful Bridgestone Potenza's for ~$800 including mounting and tax), and it sharply reduces the options when shopping for replacement tires. But a full service spare would take up a good portion of the 328 luggage area, and not having to change a tire in the snow is it's own reward. 50 miles is the minimum they'll do without pressure - you can go much further if you take it easy (and no, not 30 mph - just slow enough that the temperature doesn't build up).

11th Jul 2016, 07:26
The 530d [touring] does have a spare wheel well, but unfortunately that is where the battery and all the heavy duty electrics are installed. Run flats are a pain in the .rse. Another huge gripe with them is the ultra low profile wheels that seem to get scratched/damaged if you so much as breathe on them. Love the car but trying to keep it in pristine condition is an uphill battle and living here on the south coast there is another battle to contend with. Seagulls. Damn great white splat every day.

11th Jul 2016, 14:50
I had a 530d Shooting Brake, for about three months, never did get BBC1/2 playing or any sport, but did get to load "Pink Floyd", I never got fed up of that but wifey did, very quickly.

Sat nav not needed I am from the old A roads days so can find my way about , but run flats cost Lancashire County Council 2 tyres plus one rim due to hitting a, a sunken drainage grate, and B, a raised manhole on country roads where said Road men had not placed signs..

got rid soon after rim was replaced, went back to my old Jag with pump ups that will ride over almost anything, radio is easy and I dont have a German telling me I am going fast..:ok:

11th Jul 2016, 19:18
I replaced the run flat tyres on my Z for non run flats.
Then later ripped the sidewall out one tyre and punctured the rear.
At the time no choice but to drive home knowing the front left was completely flat.
10 miles later it finally came off the rim. No damage to the alloy.

Loose rivets
12th Jul 2016, 22:14
Well, haven driven for an age to look at a 640d with strangely badly worn 245 45 18's (strangely, since they're not the original fit and the car had only done 26,000. That seems a lot of wear in that time.) and the 640d Gran Coupe with 245 40 19 Run Flats, I was surprised to find the latter had the better ride. It was a tad hard, but it felt very 'new' despite 3X the miles. My feeling was that the first one, the one I went to see, had suffered a very, very hard quarter century.

They were both in a huge sales place which runs on a business model that must be the envy of dealers throughout the nation.

The Gran Coupe was bewildering in its complexity having some 6000 quid's worth of extras. Horrific depreciation for the original owner but despite all this I went back to the guy with the 635d who'd agreed to meet me some way with a new set of original fit Bridgestones and scrap the Chinese HiFlys. However, I'm now having to make the decision between R-F or Normal. I also find there are five different kinds of treads/structures all within a small price bracket.

Having driven for bloody hours (Two of them at Dartford at an average of 1 mph) I then went on to the sole trader. By the time I was home (average on the A12 of about 35mph) I'd had enough driving for the entire year. Then I rubbed my diddy-car on the garden wall while trying to sheppard one of 'my' pidgins - without getting my tired butt out of my seat. It wanted its supper (the pidgin, not my butt) and glared at me as though to question my right to be out all day. It'll buff out but bloody Nora, the 'new' car has eyelids over the wheels that stick out into adjacent lanes, how the heck will I be able to steer around pidgins now?

As I said before, I feel for the folk of today that will never be able to drive for hours on empty open roads. Oh-Three-sparrows and a lovely A road were magic. Imagine never, ever, being able to do that. Yellow cameras and unmarked polizii, it's all so unfair.

The deal-maker for me was that the GPS director can be shown on the Head Up Display. How cool is that? All I need now is a portal into that system to show girls with big bouncy lady-bumps and the miles will slip by all too fast . . . though it's questionable I'll know where I'm going.