[Paul1994]

What is the point of having runflats when they 1 they don't last long and 2 if you have to drive over a certain distance with a flat you will need a new tire anyway.. or have to call a tow truck..

I might as well have non RFT's and get towed anyway.

Also after having a flat in the Seattle area it seems most tire shops don't have the size i need and I have to wait at least a day or so.. If I buy a spare it takes up my trunk... Arrrggghhh.....

[splitsensetam]

yeah...they suck. Switching to Non Run Flats in 2 weeks.

[HighlandPete]

Originally Posted by Paul1994

What is the point of having runflats when they 1 they don't last long and 2 if you have to drive over a certain distance with a flat you will need a new tire anyway.. or have to call a tow truck..

I might as well have non RFT's and get towed anyway.

Also after having a flat in the Seattle area it seems most tire shops don't have the size i need and I have to wait at least a day or so.. If I buy a spare it takes up my trunk... Arrrggghhh.....

I've had mixed feelings about RFTs from their inception. (Removed them from my E91, but keeping them on my F11). I keep an open mind to how RFTs have advanced from BMW first introducing them. They work far better these days than they did at the beginning.

I feel you are simply looking at the negatives. Even tire life is debatable, as here in Europe there isn't that much difference to normal UHP tire mileage. I sense some markets have been used to high mileage from tires, but we've been preferring high grip levels for years, so used to lower mileage expectations from softer tread compounds.

The positives include convenience, say on a cold dark night, lone women drivers, dangerous road conditions, where users have clearly indicated they prefer a RFT. Plus the fear (true or imagined) where a tire blow out is more controlled.

If we use them in anger, then clearly they have done their job. There is a cost to that convenience. I know if a tire got my wife home safely one dark night, I'd be prepared to write it off as a good job done.

We must remember the "Run-on-Flat" tire is a requested safety option, one key reason BMW followed this path due to customer feedback.

HighlandPete

[BigKutta]

Its also a cost and weight saving measure for BMW, so it really buys them more benefit than it does us the users.
1) No more adding a spare rim and tire (yes my e46 had a full size wheel and tire, giving me not just a spare tire but a spare rim if I needed to swap)
2) Now there is all this free space that BMW can use for stuffing other electronics/mechanics under the trunk floor
3) Less weight so they can add weight in other places
I am sure there are more reason BMW thought of

[HighlandPete]

Originally Posted by BigKutta

Its also a cost and weight saving measure for BMW, so it really buys them more benefit than it does us the users.
1) No more adding a spare rim and tire (yes my e46 had a full size wheel and tire, giving me not just a spare tire but a spare rim if I needed to swap)
2) Now there is all this free space that BMW can use for stuffing other electronics/mechanics under the trunk floor
3) Less weight so they can add weight in other places
I am sure there are more reason BMW thought of

BMW are definitely using the benefits of more flexibility in design options and weight savings. CO2 and emissions reduction are also in the mix.

There is another issue, it is the size of wheels these days. Takes a large under floor cavity to accommodate a 275x35 R19 wheel. As wheels increase in size, wheel well allowance is getting very critical. Hence why some manufacturers can only supply a silly little space saver. What do you do with the full size wheel in the event of a puncture if you have a trunk full of luggage, even if you do have a small wheel well for a space saver?

HighlandPete

[ezaircon4jc]

Originally Posted by BigKutta

Its also a cost and weight saving measure for BMW, so it really buys them more benefit than it does us the users.
1) No more adding a spare rim and tire (yes my e46 had a full size wheel and tire, giving me not just a spare tire but a spare rim if I needed to swap)
2) Now there is all this free space that BMW can use for stuffing other electronics/mechanics under the trunk floor
3) Less weight so they can add weight in other places
I am sure there are more reason BMW thought of

4) Trying to meet stupid CAFE rules.

[ezmaass]

You're right, it's not simply a win.

But I suppose your mood may change based upon the situation. If you get a flat as you're driving to the airport - 10 miles out and would otherwise miss your flight if you had to stop and change a tire - they could be a God-send. On the other hand, if you're driving 200 miles on a vacation and get a flat as you're 25 miles into your trip, they suck. More than likely, you'll need to get it to a shop, and most won't have the tire you need - so your trip may be permanently interrupted as you wait a day to get the right tire (or make sure you can make it to a BMW shop who may stock them).

In some circumstances, I think they're great - but in others, they can be a complete PITA. The perfect compromise would have been if BMW included an RFT spare. While it may be overkill in some scenarios, in others it may just be meeting par with a non-RFT.

[gatorfast]

Agreed not a fan and will be changing to pilot super sports as soon as my run flats wear out.

[493263]

Originally Posted by BigKutta

Its also a cost and weight saving measure for BMW, so it really buys them more benefit than it does us the users.
1) No more adding a spare rim and tire (yes my e46 had a full size wheel and tire, giving me not just a spare tire but a spare rim if I needed to swap)
2) Now there is all this free space that BMW can use for stuffing other electronics/mechanics under the trunk floor
3) Less weight so they can add weight in other places
I am sure there are more reason BMW thought of

Runflats weigh more than regular tires because there's more reinforcements. The unsprung weight of runflats have a much more negative effects on MPG than regular tires, especial when all that weight is at the outer most part of the wheel. Overall, your mpg will decrease because of runflats vs conventional spare tire.

The main and only reason runflat is chosen over conventional tires is its safety aspect due to:

1. Blow out sucks and sometimes will cause you to lose control
2. Tow trucks isn't available everywhere and can take hours to get there(I was stranded on a highway for 3 hours waiting for a tow truck)
3. There are weird crazy people who will do malicious things to stranded drivers, sometimes leads to kidnapping and murder.
4. It's actually cheaper many times to drive your car to the nearest tire shop than waste time and money on a tow truck
5. Not everyone can change a driver
6. Not every shoulder on the road is friendly for a jack(had this problem before)
7. Not every road has a shoulder(in cities, this is common)
8. Don't have to worry about missing tools or broken tools
9. Less chances of riding on rims during a blow out
10. Less chances of scraping the front of your car during a blow out.

Of course there's plenty of setbacks too but we already know that. However, I would say that safety is paramount and it is better overall.

[E90Fleet]

Have had 2 incidents with run flats recently and they have been brilliant.

First was a female family member with 2 kids in the car. 95km from home at night and they hit a large bolt on the road taking a chunk out the tyre.
She just continued home at a slightly slower speed with no problems what so ever.

Would you like your wife and kids stuck somewhere out in the middle of nowhere changing a tyre ?


Second was me going to a interview and getting 3 roofing nails in a tyre.
20km to the interview and 35km back home, no problems. No having to stop on busy streets in the city and having to get dirty changing a tyre.


BMW Dealers here keep most common sizes in stock or can get them the same day if you order before 13:00.
Large tyre dealers also keep the most common sizes or can get from the manufacturers depot the same day.


Had 2 other experiences just as good in the last 6 years with run flats.

As for longevity, have easily gotten over 50,000km out of a set of runflats on a very spirited driven car, better than many other non-runflats on other cars Ive had with similar driving.

If you drive any distance on a flat regular tyre you should throw it away, just like a run flat, so no difference there.

[AP]

I too have mixed feeling about them.

I've had 2 punctures so far, both involving the same rear wheel (19 inch 275/35 Michelin Primacy)
Cost is not cheap at 400 UK pounds!

On the last occasion I drove then for 400 miles at up to motorway speed which was more that the recommended. Maybe I was just lucky but it suggests that the max of 50mph / 50 miles is perhaps conservative.

In terms of wear, I've just had my car had its first M.O.T. (UK safety check) and car has nearly 17000 miles on it now and tyre tread remains at 6mm fronts and 5mm rears. To be faire that's fairly gentle driving, no drifting etc etc.

So I see the pros and cons as this.

Pros
Allows you to continue your journey, perhaps more than the 50miles as recommended.
More boot space

Cons
tramlining
cost
limited availability although BMW seem to be the best source in my experience.


If their tramlining could be improved, I'd be a lot more happy, that's my most negative opinion on them.

[lsturbointeg]

Wow...this really sucks. Not sure which way to go when it comes to my next set of tires. With all the pros and cons.

[r33_RGSport]

Originally Posted by lsturbointeg

Wow...this really sucks. Not sure which way to go when it comes to my next set of tires. With all the pros and cons.

I would still go with regular tire.
As long the tires are not torn or got damaged where the air is leaking out in a very fast rate, you can always drive 20-30 miles with the nail attached to the tires. Especially since we have TPMS already, you can monitor the tire pressure while driving. Once it gets low, just find the nearest gas station and fill up more air or even tell them to patch it up if they have the capability to do so.
What I do, I always carry a patch tool in every car that I have.

[E90Fleet]

Originally Posted by r33_RGSport

I would still go with regular tire.
As long the tires are not torn or got damaged where the air is leaking out in a very fast rate, you can always drive 20-30 miles with the nail attached to the tires. Especially since we have TPMS already, you can monitor the tire pressure while driving. Once it gets low, just find the nearest gas station and fill up more air or even tell them to patch it up if they have the capability to do so.
What I do, I always carry a patch tool in every car that I have.

Remember that type of patch is only temporary

[HighlandPete]

Originally Posted by AP

If their tramlining could be improved, I'd be a lot more happy, that's my most negative opinion on them.

Is that the 19" wheels causing the issue? I've no problems with tram-lining on an 18" wheel set and Continental Sport Contact 3 SSR as long as I keep the pressures in the optimum range.

Tyre pressure could be a contributing cause, have you tried increasing the pressure by a couple of psi to see if that reduces the issue?

HighlandPete

[RED99HT]

Run Flats suck. I went with Michelin AS3's and its night and day compared to stock RFT. Better ride/handling/tread wear. I put a full size spare in trunk face down and problem solved. I can still put my golf clubs and several travel bags back there. If I do get a flat my full size spare will get me anywhere I need to go without worrying about traveling too far on a punctured RFT or a space saving donut. Joke is for the price of a space saver donut you can get a full size spare.

[lsturbointeg]

^^^^^^^^^^^This seams feasible. I don't mind having a spare in my trunk. Just traveling across the states I do worry about being in the middle of no-where and some Hole in the wall shop tries to rip me off. I'd rather carry a spare and change it myself. My wife has her own car So I don't need to worry about her driving the BMW and running into a flat since we have AAA.

[SonicEndeavor]

Originally Posted by E90Fleet

Remember that type of patch is only temporary

Give or take 20,000 miles
Granted, it's better to patch from the inside, but I've used these plugs and have never had one fail.

[ezmaass]

I like the benefits of the RFTs, but I'll maintain that most of the issues I have with them (regarding inconvenience of replacement) could be solved by BMW offering a spare... largely for those cases of being further than 50 miles from your destination, and/or when a replacement isn't readily available from a dealer.

[AP]

Originally Posted by HighlandPete

Is that the 19" wheels causing the issue? I've no problems with tram-lining on an 18" wheel set and Continental Sport Contact 3 SSR as long as I keep the pressures in the optimum range.

Tyre pressure could be a contributing cause, have you tried increasing the pressure by a couple of psi to see if that reduces the issue?

HighlandPete

No I haven't tried running with higher pressures. I thought if the pressures were higher than recomended (ie was on the door sticker) you'd running more on the central part of the tyre and wear that out rather than being even?
I thought the recommended pressures were to ensure even wear and even "weight" for want of a better term across the whole width of the tyre.

[The X Men]

Originally Posted by RED99HT

Run Flats suck. I went with Michelin AS3's and its night and day compared to stock RFT. Better ride/handling/tread wear. I put a full size spare in trunk face down and problem solved. I can still put my golf clubs and several travel bags back there. If I do get a flat my full size spare will get me anywhere I need to go without worrying about traveling too far on a punctured RFT or a space saving donut. Joke is for the price of a space saver donut you can get a full size spare.

Instead of saying runflat sux, you really mean the limited selection of runflat sux. I am sure if Michelin makes a AS3 runflat for your car, it will be a very good tire. There are more and more selection of runflat on the market as we speak, in another 10 or 15 years or so, runflat will be as common as airbags on cars and have a much larger selection.

[HighlandPete]

Originally Posted by AP

No I haven't tried running with higher pressures. I thought if the pressures were higher than recomended (ie was on the door sticker) you'd running more on the central part of the tyre and wear that out rather than being even?
I thought the recommended pressures were to ensure even wear and even "weight" for want of a better term across the whole width of the tyre.

You are correct, we endeavour to run a pressure that balances wear, but also after the best driving feel. Too low and we can run on the stiff sidewalls, tram-lining is one problem associated with the low side of working pressures. We must ensure we do ride the crown of the tyre.

My experience with RFTs, running above the lower end of the recommended pressures gives this wear/driving balance and reduces/eliminates tram-lining.

Driving short trips (up to 15 miles) is another reason to up the pressure a little, RFTs don't warm as fast as normal tyres, therefore can run more miles below the working pressure.

Worth trying an adjusted pressure, just to see if it reduces the tram-lining.

HighlandPete