[MARKPRIOR]

So whats peoples thoughts on these, i have them on mine but if they ever go should i replace like for like or head for std tyres?

[AP]

trawl these forums and you'll get a lot of opinions on these, both good and bad!

I've personally had 2 punctures so far and the run flats got me home (and plenty more) so was grate ful on those occasions. So they do what they say on the tin.

However that advantage does come with a lot of dis-advantages in my opinion.

Cost - very expensive. rear 275/35 19" were 400 pounds.

Tramlining - very prone to tramlining. I've increased my pressures by 0.1 bar recently and it seems to help a little but its still very much there.

Ride. Certainly with Msport suspension, you are aware of every imperfection in the road. not necessarily uncomfortable though. (many people on these forums favour the active suspensions systems as a result)

Can't comment on non runflat as I've not tried. But I seen many threads stating that they transform the car. just make sure you are geared up for a puncture as there is no spare.

[HighlandPete]

Other than the safety issues and benefit of the 'run on flat' ability, I see road quality and the actual cars' suspension/wheel sizes as a reason to think about non run-flats.

I'm an example of changing away from run-flats on my E91 330d. Catering for the eventuality of a tyre failure does cause inconvenience. Carried a spare wheel in the boot space when travelling remote or going south, so as to keep mobile if there was a failure. Always carried a jack, compressor and tyre sealant, as a back up.

This time around wanted to stay on RFTs, if at all possible. Save the hassle and keep an empty boot space. A full size wheel in the boot, uses a lot of space. In the worst case will use BMW Emergency to sort an issue, where I can't get to a destination or home.

It did mean selecting the setup carefully. I'm on 18" wheels for summer and 17" winter wheels, both sets are run-flats. No issue at all on the 535i with Adaptive Drive. Superb ride, no tramlining, copes with poor road quality and thumps over cat's eyes like normal tyres.

I couldn't risk 19" wheels, as each step up in size does change the ride quality and ability to cope with poor roads.

Remember that non run-flats will not make the same difference to the car as older generation models, or tyres, we have moved on even if not totally comparable with non run-flats. Some users say there is little difference on the F10/11, others feel more of a difference. Years back virtually everyone reported a big difference when changing tyres, some even 'too soft' after the RFT.

Differences will obviously depend on the suspension, wheel size and the tyres we choose. Still a few variables in the mix.

HighlandPete

[MARKPRIOR]

Thanks guys some good reasons for & against, gave me something to think about

[HighlandPete]

Originally Posted by MARKPRIOR

Thanks guys some good reasons for & against, gave me something to think about

I guess the key things to think about are the reasons you feel you may want to change. Whether for ride quality, costs (not just the monetary cost), safety, etc.

I know for myself I have always felt the run-flat concept is a good one, value the added safety the run-flat can give. The drive on ability, like my wife getting to a safe place, or garage/home.

My reasons for changing on the E91 were the car just didn't drive well enough, the chassis/tyres were still not fully developed back in 2006.

It is different now for sure, so not such an issue for driving feel.

HighlandPete

[morellomax]

I think there's a reason why M division and Alpina still don't specify runflats. Although they have improved, my experience is that they still compromise performance in 3 ways:
- weight: they weigh 2.5-3kg more per tyre than the non-RFT equivalent. Add rotational mass and that's the equivalent of trying to control maybe an extra 4-5kg of unsprung mass per corner, which compromises damping/ride as well as acceleration/braking;
- ride: I have tried RFTs and non-RFTs on 2 separate F10s with adaptive drive, in both cases on 18" wheels. The adaptive drive sorts out the primary ride fairly well, but it can't completely solve the secondary ride issue: the thump over pothole edges and cats' eyes. Non-RFTs still smoothed those sharp edges better;
- handling: runflats grip beautifully on dry warm smooth tarmac, but in my experience they are still more likely to give you a "heart attack moment" when a back tyre hits a pothole halfway through a bend on a cold damp B-road.
I'd say runflats are just ok, and then only if you stick to 18s or smaller. If you're obsessive about ride quality, or you want to go bigger than 18s, I'd go non-runflat.

[HighlandPete]

A fair assessment morellomax, and good observations.

I've no doubt that in my situation I'd have a slightly better car, changing to non run-flats. I'm currently living with the compromises and pretty happy with my choices. Have no real issues replacing with another set of Continental Sport Contact 3 SSR.

I'll be facing that decision either later this summer, or possibly when I put my summer wheels back on next spring. I've thought of fitting Michelin PSS, (would love to be on a set) but will seriously weigh up the 'for and against' issues. Certainly not a case of "can't wait to get the RFTs off", like it was in the E91.

HighlandPete

[Pottsy]

morellomax,

That's good to read. As soon as I got my F10 I chucked on the non run flat 17" winters. The ride was perfect (on AD). As in, absolutely perfect. Being winter tyres they were a bit squidgy in corners, as if you could feel the tread blocks squirming, but I was happy.

When my 18" run flats went on, it all went to pot. I sadly have the stupid road-roller rear wheels (staggered setup, 275's on the back) and the weight was astonishing. I could whizz the 17's on and off no issue, but those needed all my might. And the secondary ride is now dreadful, the tramlining is a joke and I am grumpy. I have a feeling that if had had a square setup of 245's all round (like HP) then that would be better - but I'm stuck with these for now.

Just can't wait to rip them off and bung on some MPSS too! I have an AA card, which I reckon is the lightest and cheapest way of solving the puncture issue...

If I take these run flats off now - what will their shelf life be? Thinking about keeping them and putting them back on at disposal time.

[martin mustang]

Very happy with my Michelin Super Sport normal tyres on 18inch, the comfort is far from the RF one’s but it is the case if you don’t try your car with non RF you never know in my case it was down to 2 reasons, 1 - My winter tyres set was normal when I switched back to the my original RF set felt the difference straight away, and to be honest it was a big difference! The 2nd reason was down to my dealer changing part of the suspension back to metal from alum following a normal service, apparently for UK and Ireland BMW dealers are asked to check some Alum part of the suspension and instructed them to change to metal, due to the state of the roads! I am from London and moved out here to the West of Ireland to my knowledge the roads are more or less the same apart if you mainly do motorways!

[morellomax]

Pottsy - I will probably have a set of non-RFT Dunlop SportMaxx RTs on 17s available soon. The car rides beautifully on them like it did on your winter non -RFT 17s. Quite grippy even though they're 235/55 all round.

I won't keep them because they don't have the pressure sensors built in, and the car keeps complaining about it, and I'm about to mount a set of 18s with non-RFTs that do already have them built in (will do it as soon as I find the locking wheel nut that span off in the road somewhere when I put the 17s on......)

You're not wrong about the weight differences:
- 273/35 19's with a typical runflat tyre = 27-28kg
- 235/55 17's with a typical non-RFT = 20-21kg

[morellomax]

Originally Posted by HighlandPete

A fair assessment morellomax, and good observations.


HighlandPete

Thanks Pete. I read a lot of your observations about suspension and wheel options on the F10/11 before buying my first one, and found them very helpful.

I know a lot of people still buy a 5 series hoping for an exciting drive. I'm not one of those people: I'm looking for a way of getting S-class comfort and refinement without having to buy an S-class. A small-wheeled, non-RFT equipped F10 with AD is about as close as I've got.

[HighlandPete]

How things change... when I had my first BMW (E12 528) there was one wheel size for the model, 14 x 6J (steel or alloy) shod with 195/70 R14. Pumped them up to the recommended 30psi, front and rear, never had to think any more about them, or how they worked on UK roads.

Fast forward to the present time and we have to plan, scheme, modify and still can find we have got it all wrong.

My own case, I demo'd several suspension and wheel options and learned that for my conditions AD would be essential to enjoy the F11, going bigger than 18" was going to be a gamble. One key reason, temperature still has an influence on RFT performance.

Also had to consider the winter option, could I risk running the same 18" rims (Style 350M) winter time, with winter RFTs? Or would down sizing to the 17" be a prudent move?

What I've found the 17" winter RFT is a very smooth running wheel, doesn't stiffen up when cold to the detriment of the ride and handling. In fact it is very good at coping with road imperfections and giving excellent secondary ride comfort.

How I sum it up, a 17" winter RFT, runs in cold temperatures like the 18" summer RFT does in warm conditions. Hardly a run-flat trait coming through to the cabin, or through the steering.

I fitted my summer wheels a couple of weeks back on a warm afternoon, about 15C, went out for a test drive. Virtually no difference than the winter tyres over the previous weekend, in colder conditions. Since fitting have had a few cold days and can feel a slight deterioration in ride quality. Last week was up to around 18C and tyres were fine, no negative issues at all.

I just get the occasional reminder that I'm on RFTs, the odd road ridge or imperfection which puts a slight shudder into the suspension, but not enough to wish I'd picked any other wheel combination.

BTW, my roads are not all good surfaces, a Bridgestone Field Engineer called them "challenging", when sat as passenger in my E91.

HighlandPete

[Pottsy]

Just weighed one of my 17's - 20.5 Kg (225 Avons).

I too want S Class Merc comfort, but also half reasonable A road action. I know, an impossible dream. But hence my choice of AD with 18's.

I'm done buying more alloys for the time being, so I'll give MPSS's a go first.