How much extra comfort ditching the run flats?

[35i-Nut]

So currently on 296 19" alloys with Bridgestone OEM runflats , adaptive suspension , H & R springs

How much extra comfort can be achieved by ditching the run flats ? 25% ? 50%

Many have said there is a massive difference , debating whether to finally pull the trigger and buy new 19" rims and non run flat tyres

Will be a tad miffed if the ride quality doesn't improve with losing the run flats

Any experiences to share ?

 

[Z4Rick]

I switched mine recently to snow/wet non-runflat tires on the stock rims. First thing I noticed was a smoother ride; second thing was a quieter ride. I lost 8 or 9 pounds per wheel and the loss of unsprung weight felt noticeably quicker in steering. I would do it again in a heartbeat, but get a can of tire seal or equivalent for the trunk, and keep your eye out for 'road hazards'.

 

[markplant]

You might also be able to get some more side wall as well depending on what clearance you have
Either go same widths an up a profile or keep same profile an a up a size on width
If Mr Wilks drops on this thread he normally has very good tyre size advice

 

[goldbcfc]

How much extra comfort can be achieved by ditching the run flats ? 25% ? 50%

Probably 25% those RFT are just shocking far to hard at this time of year they must slide a lot too in cold. I hate RFT shakes the cabin over every rough surface or bump. Horrible ride not just bmw all cars.

 

[john-e89]

From my perspective, I was very happy with the Bridgestone run flats, much better than on the E85, so much so I dawdled and TBH I only changed when Kermit on here was selling a set of all but new MPSS's. I won't ever go back to run flats, the difference is amazing. They are so much more supple and borderline soft but keeping a level of feel and grip on a different level. It's transforms the car imho. The oversteer is reduced, the front turns in much easier with more grip, the whole car feels more planted and stable. Bold statement but I would virtually guarantee you wouldn't regret the swap.

 

[Mobeer]

How much of an impact on your insurance?

 

[csquire4]

I've heard the 3rd generation run flats are much better than early run flats.

Personally, I've had run flats on a 1 series coupe and E60 and can't stand them. Normal tyres are cheaper, quieter, more comfortable & more responsive. Make the change as soon as your existing ones wear out is my advice. Ideally change them all at he same time but at least both on the same axle at the same time.

www.camskill.com is a good place to buy and then go to your local independent fitter, they'll charge about £10 a wheel to fit and balance.

 

[AnubisZed]

How much of an impact on your insurance?

I second this question. I assume you've all told your insurance companies that you are no longer running on Run Flats?

 

[DMC63]

I had to replace a good Bridgestone 255/35/18 yesterday for the same in RFT. £221!!!! It has already been run flat by the previous owner so the 2 nails and the 1 screw in the same tyre couldn't be repaired. Gutted. Had my pal in the car for a spin and he said my suspension (B12 kit) was like a racing car. It's a bit of a gamble whichever way you look at it. I can't comment on comfort because I've only driven on RFTs. The RFTs are expensive, but can be repaired. The non RFTs are cheaper but if you get a flat and fill it with tyreweld then the tires trashed.
So there's the the possible repair over comfort or comfort over impossible repair. Maybe some tyre fitters will clean out the gunk and refit.
When I bought the Z I was fully prepared for the roadster experience. In my mind I envisaged, hot in summer, top down, hard steering, tough gear changing, rigid and bone shaking ride with my arse on the ground. Winter time, cold seats, steering wheel, gear shift, hard top on and a bone shaking ride. I've not been disappointed. I like that about a roadster, like the old MGs and Spitfires. It's a sports car. I don't want to dilute that experience. Each to their own though. Maybe the older you get the more 'comfort' you want. The music gets less energetic and quieter, you go out less, your in bed at a reasonable time, and you wear 'sensible' clothes favoring practicality over style...And a nice quiet comfortable car. LOL :rofl: Maybe it's time to buy a Toyota Prius :driving:

 

[goldbcfc]

Pirelli P zero cost me £200 each and were awful gave me no confidence in the rain or even slightly damp surface in morning. Replaced with non RFT that cost £400 half the price and out preformed them. RFT never agin !!!!!

 

[Smartbear]

I had to replace a good Bridgestone 255/35/18 yesterday for the same in RFT. £221!!!! It has already been run flat by the previous owner so the 2 nails and the 1 screw in the same tyre couldn't be repaired. Gutted. Had my pal in the car for a spin and he said my suspension (B12 kit) was like a racing car. It's a bit of a gamble whichever way you look at it. I can't comment on comfort because I've only driven on RFTs. The RFTs are expensive, but can be repaired. The non RFTs are cheaper but if you get a flat and fill it with tyreweld then the tires trashed.
So there's the the possible repair over comfort or comfort over impossible repair. Maybe some tyre fitters will clean out the gunk and refit.
When I bought the Z I was fully prepared for the roadster experience. In my mind I envisaged, hot in summer, top down, hard steering, tough gear changing, rigid and bone shaking ride with my arse on the ground. Winter time, cold seats, steering wheel, gear shift, hard top on and a bone shaking ride. I've not been disappointed. I like that about a roadster, like the old MGs and Spitfires. It's a sports car. I don't want to dilute that experience. Each to their own though. Maybe the older you get the more 'comfort' you want. The music gets less energetic and quieter, you go out less, your in bed at a reasonable time, and you wear 'sensible' clothes favoring practicality over style...And a nice quiet comfortable car. LOL :rofl: Maybe it's time to buy a Toyota Prius :driving:

Ive used tyreweld and the fitter just washed it out-no problem at all
Rob

 

[bmwaddict]

How much of an impact on your insurance?

I second this question. I assume you've all told your insurance companies that you are no longer running on Run Flats?

I haven't, and I think you'll find nobody else has, why would you? Never heard of any insurance company asking anything about this, it's not exactly a modification, and I see no reason to. Driving on a flat tyre destroys it whether it's a rft or not. I'm in the tyre industry btw, and never heard of any insurance company mentioning tyres let alone going into specifics.

 

[DMC63]

I had to replace a good Bridgestone 255/35/18 yesterday for the same in RFT. £221!!!! It has already been run flat by the previous owner so the 2 nails and the 1 screw in the same tyre couldn't be repaired. Gutted. Had my pal in the car for a spin and he said my suspension (B12 kit) was like a racing car. It's a bit of a gamble whichever way you look at it. I can't comment on comfort because I've only driven on RFTs. The RFTs are expensive, but can be repaired. The non RFTs are cheaper but if you get a flat and fill it with tyreweld then the tires trashed.
So there's the the possible repair over comfort or comfort over impossible repair. Maybe some tyre fitters will clean out the gunk and refit.
When I bought the Z I was fully prepared for the roadster experience. In my mind I envisaged, hot in summer, top down, hard steering, tough gear changing, rigid and bone shaking ride with my arse on the ground. Winter time, cold seats, steering wheel, gear shift, hard top on and a bone shaking ride. I've not been disappointed. I like that about a roadster, like the old MGs and Spitfires. It's a sports car. I don't want to dilute that experience. Each to their own though. Maybe the older you get the more 'comfort' you want. The music gets less energetic and quieter, you go out less, your in bed at a reasonable time, and you wear 'sensible' clothes favoring practicality over style...And a nice quiet comfortable car. LOL :rofl: Maybe it's time to buy a Toyota Prius :driving:

Ive used tyreweld and the fitter just washed it out-no problem at all
Rob

That's good to know. Atm I've got a brand new Pirelli on the front and a Bridgestone on the back both RFTs. So it's gonna be a looong time before the window of choosing the comfort option presents itself. I'm a bit of a purist at heart and look at the ride as the way it was first released by BMW in 2003. Their vision after a lot of testing etc. With it being the 'original' Z4 I kinda expect it to be the best they could design before they started getting lots of 'feedback' and started to change things. They fell short on the aesthetics though. OAP Leather handbrake cover and gear shift knobs in a roadster? Nooooo! and the non sports seats should never have been put in, they belong in an estate agents. They should've put sports seats in all of 'em. What else....Oh yeah, All cars should've had a B12 kit as standard....and supercharged :stir:

 

[AnubisZed]

How much of an impact on your insurance?

I second this question. I assume you've all told your insurance companies that you are no longer running on Run Flats?

I haven't, and I think you'll find nobody else has, why would you? Never heard of any insurance company asking anything about this, it's not exactly a modification, and I see no reason to. Driving on a flat tyre destroys it whether it's a rft or not. I'm in the tyre industry btw, and never heard of any insurance company mentioning tyres let alone going into specifics.

My point was that if BMW supplied the car as a specification with Run Flats and you have an accident and are running Normal tyres then surely it could be seen as a departure from spec and thus "could" be a reason for them to render your insurance invalid.
Standard insurance company question is "Any modifications" which translates to "have you changed ANYTHING?", if you answer "NO" then they "could" have you by the short and curlies.

I'm sure this could be seen as a stupid question from a newbie, and I may well be a newbie here but I've been on internet car forums since they were invented so I know to ask anything that isn't already stated because if nothing else it helps others.

 

[Magicarcher]

Just bought a Z4 which I pick up on Thursday, the first change I will make is to ditch the runflats once the tyres need replacing.

I can't speak for the effect they will have on a Z4 but I can for a Mini. I endured 70k miles on runflats on my Mini and only kept them that long because of convenience and perceived safety advantages. Having changed to conventional tyres now I would never go back to runflats. The ride on runflats is awful, they have very little compliance over bumps and potholes and aside from the discomfort I believe they have to result in more wear and tear on the suspension components because if the energy of a bump is not being absorbed by the tyre, it has to be absorbed by the suspension.

But it is a personal thing. I would suggest you try to locate someone with 19inch non runflats and compare the two cars over a road that is good for bringing out the characteristics of good suspension.

 

[benv6]

In my previous e85 the non-RFT made a huge difference, I wouldn't even measure it because it was just a different car.

I spoke to my insurance and they stated that as long as the tyres are legal then it shouldn't be considered as a mod.

Now for the e89, the RFT weren't that bad when new (When I bought the car) but now I got 4mm left at the back and about 5-6mm front and the roads have been constantly wet. I must admit the handling is terrible even-though I got used to it, I will be be ditching the RFT asap.

 

[Ewazix]

I contacted my insurance company when I swapped out the RFT's on my e85 and they were not interested but "made a note". In reality some BMW group models like my Mini can be specified with either, the e85 M cars never had them so long as the tyres are the correct speed/load rating I can't see an issue.

Proof of the pudding...... who has ever heard of an insurance co turning down a claim on a car because non RFT's were fitted? :tumbleweed:

 

[35i-Nut]

Great discussion guys , thanks for your comments

I have always had sports suspension on most of my cars , I'm used to firm sporty rides but to be honest the comfort in the Z4 is really bad with 19" rims and RFT on UK roads. The SE seats are also flat as a pancake and offer me little or no support.

Think I may try the new alloys / tyres after Xmas and see how I get on , will feedback my findings

 

[35i-Nut]

Is there any issues with fitting non run flat tyres to the 296 rims ? I.e are there any special design features of the rim meant to suit a RFT ? and normal tyres cannot go on ?

I may go for just tyres first and get new alloys at a later date

 

[Ewazix]

Is there any issues with fitting non run flat tyres to the 296 rims ? I.e are there any special design features of the rim meant to suit a RFT ? and normal tyres cannot go on ?

I may go for just tyres first and get new alloys at a later date

I'm happy to be shot down on this but I always understood RFT rims have an extra ridge to retain the deflated tyre, so RFT cannot be safely fitted to non-rft rims, but the other way around is fine. The construction is explained here http://webcache.googleusercontent.com/search?q=cache:8OBFnyLdIBYJ:www.bmw.com/com/en/insights/technology/technology_guide/articles/run_flat_tyres.html+&cd=2&hl=en&ct=clnk&gl=uk