[dopper99]

Slight change of subject, but I agree with the thread title, run flats are utter utter rubbish - well certainly in the E90 anyway. This best thing I ever did with my car was to swap them all over to non run flats when the rears ran down after 12K miles.
I had a "spirited" drive back from the Midlands yesterday down the Fosse Way and the way the car gripped with non run flats was awesome in this nice dry weather. None of the nervousness and skipping that I used to get in with the run flats at the limit. However, it does encourage higher speeds due to much better grip - so need to be careful.

For sure, non run flats release the untapped potential from the car that you dont get when the car is on run flats. They give you so much more from the car and as a result is far more enjoyable to drive.

I'm not into modding cars and not one to deviate too much from OEM spec, but by a mile, this is the best thing I could have ever done to my car. To the point that before I changed the tyres I thought about changing the car, but now I'll hang on to it for a while longer as its such a good drive now.

Having said all of that, the F30 is supposed to ride a lot better with the run flats fitted so you guys may not have the same problems as the E90. I'd be interested to hear the first reports of anyone who may decide to take the plunge and fit non run flats to their F30.

[RobUK]

Originally Posted by claykin

You should attach two strong electromagnets to the bottom edges of your front bumper to pickup nails b4 they reach your tires.

And BTW, it can be repaired but I also understand the shop declining. On my E90 I had 2 tires that got nails very close to sidewall. I had both repaired with patched from inside. Reason why tire shops don't like patching near sidewall is because of the sidewall flex typically would cause the patch to fail (and because tire OEMs specifically recommend against it). RFTs flex so little the patch can survive as my 2 did. One of them for over 7K miles.

What tires are on your car?

I'm on the Bridgestone Potenza S001's (225/45 R18 front and 255/40 R18 rear).

[RobUK]

Given the rate I'm picking up punctures, it would seem prudent to renew my tyre insurance. Car2cover seem to have the dumbest condition ever... you need to have purchased the car in the last 30 days to get a quote. So with 1yr old car bought new I'm ineligible, but if I bought the exact same car less than 30 days ago I can get covered

ALA weren't much help either as they'll only do tyre insurance in association with GAP insurance. So looks like I'll be stuck with a new BMW policy... and I'll get the new tyre-wear clause in this one no doubt

When I had my E81 there were a few guys over at babybmw.net who had ditched their RFTs for standard tyres and said it was a vast improvement. I've heard the F30 suspension is 'tuned' for RFTs and that dealers and BMW UK frown on the use of non-RFTs, something along the lines of any fault developing that they can attribute to the use of non-RFTs won't be covered by warranty

[HighlandPete]

Originally Posted by RobUK

I'm on the Bridgestone Potenza S001's (225/45 R18 front and 255/40 R18 rear).

If anyone is thinking of changing from the S001, for improved comfort and grip, the Vertical Stiffness Index (VSI) is rated at 106, compared to a non run-flat S001 at 100. So the RFT is getting quite close to the non run-flat for comfort levels and associated tyre dynamics.

Compared to the Potenza RE050 of the E90 era (with a VSI of 126), current Bridgestone is a lot softer, we have moved on. There will not be the same sort of radical change as we had with our E9* models.

HighlandPete

[jbtco]

Will have to wait and see on the puncture front, 3 weeks into F31 xdrive ownership so early days. Had X5 for 18 months and 1 puncture on run flats, tyre monitor didn't go off so only found out when handling was even worse than normal.

So far pleasantly surprised by the Potenza S001s from a comfort viewpoint even on 19s in sport mode.

[swanseahammer]

Originally Posted by HighlandPete

If anyone is thinking of changing from the S001, for improved comfort and grip, the Vertical Stiffness Index (VSI) is rated at 106, compared to a non run-flat S001 at 100. So the RFT is getting quite close to the non run-flat for comfort levels and associated tyre dynamics.

Compared to the Potenza RE050 of the E90 era (with a VSI of 126), current Bridgestone is a lot softer, we have moved on. There will not be the same sort of radical change as we had with our E9* models.

HighlandPete

Pete do you have a link to where you can get the vsi ratings for different tyres?

[dopper99]

Originally Posted by RobUK

......dealers and BMW UK frown on the use of non-RFTs, something along the lines of any fault developing that they can attribute to the use of non-RFTs won't be covered by warranty

Its alright for BMW to fit non run flats to "M" cars as standard (ie M3, M5 etc..), but then they get the arse when owners choose to fit non "M" cars with non run flats.
One rule for one and one for another. Seems all this BS talk about safety with run flats goes out of the window when it comes to "M" cars. If run flats were that good, they would fit them to ALL of their cars including "M"s.
Its an "easy" way for BMW to improve the handling for "M" cars, just dont fit run flats.

I would be happy to eat my words if the next M3 comes fitted with run flats as standard.

[dopper99]

Originally Posted by HighlandPete

If anyone is thinking of changing from the S001, for improved comfort and grip, the Vertical Stiffness Index (VSI) is rated at 106, compared to a non run-flat S001 at 100. So the RFT is getting quite close to the non run-flat for comfort levels and associated tyre dynamics.

Compared to the Potenza RE050 of the E90 era (with a VSI of 126), current Bridgestone is a lot softer, we have moved on. There will not be the same sort of radical change as we had with our E9* models.

HighlandPete

Yes I know you've said in the past that the E9X was far, far worse on run flats compared to the F3X/F1X. For me its not only the ride comfort but the lack of grip and nervousness when cornering are others issues with run flats. But again, prob only with the E9X.

[HighlandPete]

Originally Posted by swanseahammer

Pete do you have a link to where you can get the vsi ratings for different tyres?

If it was only that simple. I've never come across a comparison for tyre vertical stiffness across the brands, would be so useful. To my knowledge using a tyre vertical stiffness (or deformation) index is usually only found in the technical test data/papers. Like in the Bridgestone testing, where 100 is used as the baseline on the reference tyre, and other tyres are measured (with same pressure and load) against that reference tyre baseline figure.

Having charts of a tyre's vertical stiffness would be so useful in comparing across the brands in any tyre segment, run-flat, high performance, touring tyres, etc.

It wouldn't be a perfect answer, as a tyre's vertical stiffness is different with pressure and load, but a realistic midrange pressure/load comparison test would be a good guide.

HighlandPete

[HighlandPete]

Originally Posted by dopper99

Yes I know you've said in the past that the E9X was far, far worse on run flats compared to the F3X/F1X. For me its not only the ride comfort but the lack of grip and nervousness when cornering are others issues with run flats. But again, prob only with the E9X.

I have found that the latest tyres are also better with grip, particularly noticed on poorer road surfaces with early RFTs, and do not have that same nervousness and unpredictability as the previous generations.

I've lived with my 535i for almost 10 months now, through the seasons and on both summer and winter run-flats. I just get the occasional glimpse that the car is on a run-flat tyre with the summer tyres, nothing on the winter ones. Nothing serious, but just a little reminder that tyre walls are a bit stiffer than a typical high performance tyre. So different from my experience in the E91 330d, where the tyres were definitely messing the car most of the time, and transformed the car when I changed to non run-flats.

HighlandPete

[Mr NSB]

I have had my car 10 weeks and just had my second puncture in two weeks and two thousand miles today.

Luckily it didn't completely deflate so I was able to drive on. I took it to my preferred tyre supplier (Micheledever Tyres, near Winchester) and they have repaired it

[ZigmundUK]

Hey so I've for tyre insurance right. If its a repairable puncture, can I get it replaced, keep the other tyre, get it repaired then sell it?