Changing Run Flats for Standard Tyres

[Jezh]

The M135i is due some new boots. I want to fit Michelin PS4's but they don't appear to be available as run flats. There are conflicting discussions all over the internet about whether it is good or not to change from OEM fitment RF's to standard tyres so thought I would turn to the great and good of this forum for the definitive answer

[Swervin_Mervin]

Just do it. Ignore the nonsense on the internet. They'll be a million times nicer.

I did it years ago on my E91 330i and never regretted it

We switched our 125i late last year to non-RFT Goodyear F1s, and that runs the same tyre sizes as the M135i I believe, and also has adaptive chassis. It's transformed the ride and NVH, and without detriment to handling imo.

[Carlos]

The M140i doesn't come with runflats so no reason why you don't switch over.

[Foz]

Mine did, and in fact I have a full set of unused tyres (and wheels and TPMS) if you want to make an offer for the tyres RE050 Bridgestones

[Jezh]

Thanks chaps. I think I will take the plunge.

So thinking about wider issues, no room in the car for a spare so if one of them springs a leak what are the best options out there for a temp fix to at least get me to a garage, massive blowout aside?

Do you think I need to advise insurers?

[240PP]

Older car but I changed the runflats on my Z4 for standard Bridgestones and it felt like a different car afterwards. I didn’t notice a massive change in ride but the handling was SO much more progressive. No more back end skipping about over manhole covers mid-corner and I had way more confidence to press on.

Tell your insurance company if you do change them, there shouldn’t be any charge to do so.

[Foz]

RFT’s have come a log way in the last few years by all accounts

[Jezh]

Older car but I changed the runflats on my Z4 for standard Bridgestones and it felt like a different car afterwards. I didn’t notice a massive change in ride but the handling was SO much more progressive. No more back end skipping about over manhole covers mid-corner and I had way more confidence to press on.

This is primarily what I am after. It scares the crap out of me sometimes when it feels like the back wheels have left the road for no real reason other than a small rut in the road or similar.

[Swervin_Mervin]

Bollox to telling the insurers. You're fitting standard legal tyres. Asking the question is inviting stupidity on their part. Save yourself the hassle.

As for alternatives to a space saver, you could get cans of tyre gunk if you want. Chances are that most punctures you'll be able to drive on - I've been driving the last 10 years with cars on std tyres and no spare and any puncture I have had has been slow enough to get to somewhere safely. Be better getting an electric pump imo. The cans of gunk I had in both cars had/have probably gone off without being used

The mrs did pop one of her new std tyres on a pothole, just before joining a motorway, and managed to get several miles at her usual speed before it started to feel bad enough to warrant coming off AA man fitted a space saver to get her home. Event tyres were out within a day to fit a new tyre.

[240PP]

Bollox to telling the insurers. You're fitting standard legal tyres. Asking the question is inviting stupidity on their part. Save yourself the hassle.

If the car comes with RFTs then the insurer may see that as changing the original configuration of the car. Could be an easy get out for them in the event of a claim.

Mine just said they had made a note of it but didn’t charge me any extra.

[Swervin_Mervin]

Nope

[Jezh]

All ordered from Blackcircles as they had a £40 off 4 Michelin PS4's. Going to be fitted at local tyre place Thursday morning.

I can see both sides of the insurance question but will probably not mention it for now. Also I found this comment on National tyres guidance regarding whether to change RF's for standard tyres

From BMW
BMW promote run flat technology because of its advantages for driver comfort and safety. They point out that when run flats are fitted as original equipment, then vehicles' braking and suspension are set up accordingly, so changing to conventional tyres may affect the handling characteristics of your car. However, they do say it is possible to fit conventional tyres.

It is also interesting to me that such a widely renowned and performance oreinrtated tyre from a major manufacturer is not available as a run flat especially when it was apparently developed with BMW amongst others.

[IanF]

All ordered from Blackcircles as they had a £40 off 4 Michelin PS4's. Going to be fitted at local tyre place Thursday morning.

I can see both sides of the insurance question but will probably not mention it for now. Also I found this comment on National tyres guidance regarding whether to change RF's for standard tyres

From BMW
BMW promote run flat technology because of its advantages for driver comfort and safety. They point out that when run flats are fitted as original equipment, then vehicles' braking and suspension are set up accordingly, so changing to conventional tyres may affect the handling characteristics of your car. However, they do say it is possible to fit conventional tyres.

It is also interesting to me that such a widely renowned and performance oreinrtated tyre from a major manufacturer is not available as a run flat especially when it was apparently developed with BMW amongst others.

Because full fat ///M cars don’t use run flats.

[Jezh]

Having had them fitted yesterday morning I can report the following

Much less road noise
More compliant ride over our shite roads
Doesn't feel as twitchy when pressing on
Haven't had any incidents (yet) where it feels like the rears have completely lost contact with the road
However, I would say steering possibly not as sharp as before but I will get used to that.

Overall verdict, it was never going to completely transform the car handling wise (think I maybe paying Birds a visit next for that) but it is certainly a worthwhile improvement if like me you need to change all 4 tyres at the same time. I understand it is a no no to mix standard tyres and RF's on the same vehicle.

[Swervin_Mervin]

Yeah, same findings as us. Doesn't have much bearing on most aspects of handling, but I find the chassis just feels like it copes better with the reduced mass, and ride & nvh is notably improved.

[Zonda_]

The 4 Series needs front tyres and I will be replacing the run flats with normal as I find the runflats very noisy. The rears still have a few k left on them so they'll have to wait.

[Jobbo]

Bollox to telling the insurers. You're fitting standard legal tyres. Asking the question is inviting stupidity on their part. Save yourself the hassle.

If the car comes with RFTs then the insurer may see that as changing the original configuration of the car. Could be an easy get out for them in the event of a claim.

Mine just said they had made a note of it but didn’t charge me any extra.

If it came on Michelins and you fit Ling Longs, that could also be changing the original configuration, by the same rationale. But if they are the right size, load and speed rating you’re doing nothing which needs to be notified to insurers.

Unless you paint the sidewall lettering white

[Jezh]

Zonda, as I said in my last post I am led to believe mixing RF's and standard tyres on the same chassis is not a good idea. Obviously this is only based on the internets opinion.

Jobbo, my thoughts exactly!

In other news, maximum attack mode is far less scary now, for that alone it has been a worthwhile investment.

[Zonda_]

Zonda, as I said in my last post I am led to believe mixing RF's and standard tyres on the same chassis is not a good idea. Obviously this is only based on the internets opinion.

Jobbo, my thoughts exactly!

In other news, maximum attack mode is far less scary now, for that alone it has been a worthwhile investment.

The rears will need to be replaced in a matter of weeks anyway.

[Zonda_]

I'm struggling to find tyres for the 4 Series, plenty in the front size but only a limited selection in the rear size.