The great run flat tyre debate.

[FurtiveFreddy]

msej449 said:

Non-runflats are significantly more dangerous than runflats when suddenly deflating at speed. Look at the videos e.g.

https://www.youtube.com/watch?v=4FOIubWv6Cs

If you used your brain rather than shouting abuse, you might posit that the probability of this happening is so low that it's not worth any compromise in handling, which is a reasonable position.

I don't know why I'm making your argument for you - perhaps I should just swear and it would be more convincing?

Edited by msej449 on Tuesday 23 January 19:12

I didn't shout and please feel free to swear all you like. You're still talking bks though.

[msej449]

Sigh. So are you just going to type abuse every time someone disagrees?

I go to the trouble to search for a video of an actual, side-by-side track test of runflat and non-runflat blow-out to illustrate my point, and your considered response is to just swear. Again.

Edited by msej449 on Tuesday 23 January 22:33

[Dino D]

Mr Tidy said:

Dino D said:

I’m giving them a go on a Smax ford (it has no spare but does not have runflats as standard - would prefer the convenience of a runflat on a family bus). It’s has big sidewalks so hopefully no real downside to the ride.

Just a thought, but does the car have any Tyre Pressure Monitoring System? If not, you really don't want run-flats on it as you'll never know if you have a puncture.

Yes it does, I think all cars after a certain year did. This tyre is for cars that didn’t have RFT but they say you must have TPMS to be able to fit (normal rims are fine they say).
Think it’s an MOT issue too if you don’t have TPMS abut have RFT.

[FurtiveFreddy]

msej449 said:

Sigh. So are you just going to type abuse every time someone disagrees?

No, only when someone talks bks.

[Speed addicted]

Dino D said:

Mr Tidy said:

Dino D said:

I’m giving them a go on a Smax ford (it has no spare but does not have runflats as standard - would prefer the convenience of a runflat on a family bus). It’s has big sidewalks so hopefully no real downside to the ride.

Just a thought, but does the car have any Tyre Pressure Monitoring System? If not, you really don't want run-flats on it as you'll never know if you have a puncture.

Yes it does, I think all cars after a certain year did. This tyre is for cars that didn’t have RFT but they say you must have TPMS to be able to fit (normal rims are fine they say).
Think it’s an MOT issue too if you don’t have TPMS abut have RFT.

I think the wheels for run flat tyres are different, not sure you can just switch to them if it didn’t have them in the first place.

[bodhi]

I swapped my old RE050 RFTs for some normal PS4s in 2016, and 20k miles later I can safely say it's one of the best car mods I've ever done. Ride and handling transformed, masses more grip , and all the dashboard rattles that were driving me up the wall disappeared over night.

I'm getting near the wear indicators on the rear so will need new boots soon - there is no way in hell I'm putting RFTs back on again.

[Swervin_Mervin]

Monty Python said:

Swervin_Mervin said:

In my case of moving from the same tyre in RFT to non-RFT, I'm talking about wrestling the steering wheel one day just to keep it in a straight line, and wincing over anything resembling a bump, to practically being able to drive no hands in a straight line and thinking "what bump?".

It is that marked a difference.

Herein lies the problem - I've never experiences the kind of "wrestling" you have - and that's in 8 years of driving on a mix of 18/19" runflats of various types.

Had it on my E91 as well. It's not surprising that they would tramline more, as they have a far stiffer sidewall afterall. Throw some rural UK roads into the mix and it's a lovely recipe for abysmal handling.

Have you ever got down to less than half tread depth on RFTs? That's when the ride and handling really becomes awful.

[Speed addicted]

bodhi said:

I swapped my old RE050 RFTs for some normal PS4s in 2016, and 20k miles later I can safely say it's one of the best car mods I've ever done. Ride and handling transformed, masses more grip , and all the dashboard rattles that were driving me up the wall disappeared over night.

I'm getting near the wear indicators on the rear so will need new boots soon - there is no way in hell I'm putting RFTs back on again.

I found the same thing with the BMW 645, it's fixed the jiggly ride over broken surfaces and it certainly generates more grip. It's not night and day but I certainly won't be going back. I'd say it feel similar to going down a couple of inches on wheel size.

[Speed addicted]

msej449 said:

Non-runflats are significantly more dangerous than runflats when suddenly deflating at speed. Look at the videos e.g.

https://www.youtube.com/watch?v=4FOIubWv6Cs

Edited by msej449 on Tuesday 23 January 19:12

Ok, if you're driving fairly quickly, then have a blowout, then swerve hard you may have some instability that having runflats would reduce.

It's not a hugely likely set of circumstances though, I had a sudden total deflation in a rear tyre on a 1980 BMW 320 (not the most stable of things in the first place) at 50mph when I clipped a brick on the road and it tore the tyre side wall. The car was easily controllable if a little loose.

I've also had sudden punctures on the rear tyres of motorbikes, again managed to stop safely without any drama.

For me the difference in ride quality and grip on less than perfect surfaces is worth the risk..

[VerySideways]

You know a runflat can have a blowout too, right?

[bodhi]

I had a blowout at a speed not too far off the fastest a Cinquecento Sporting will go. Obviously I died twice in the process, but it was remarkably straightforward to bring to a halt.

[E-bmw]

Speed addicted said:

I think the wheels for run flat tyres are different, not sure you can just switch to them if it didn’t have them in the first place.

You are right in so much that you can't fit run flats to non-run-flat wheels, you can, however do the reverse.

[RobM77]

On my last E90 (a 2007 320d SE) I used to regularly go from run-flat standard BMW fit Conti-sport contacts (205/55/16 I think) to Dunlop Winter Sport non run flat tyres. Aside from the obvious changes in tread deformation when cornering (which was horrible on the winters), the non runflats gave a nasty bouncy ride. Basically, the tyre sidewall is part of the suspension and that's what an RFT equipped BMW's suspension is tuned for - change an element in that and it's no longer as designed. I couldn't wait to get the RFTs back on in spring each year.

I currently own another E90, this time a 2010 LCI 320d ED, and that doesn't have RFTs, shunning them for Michelin Energy Saver tyres. This isn't really relevant to the discussion though, because the ED suspension was notoriously bad. I switched to Birds' suspension and kept the Energy Saver non-RFT tyres. It's a vast improvement, but the Birds kit is designed to work with non-RFT low profile 17s and 18s, not my non-RFT balloon profile tyres. I can't help wondering if I could improve the ride and handling further by switching to RFTs to get closer to the sidewall stiffness that the non-RFT larger tyres have....

[smashy]

RobM77 said:

On my last E90 (a 2007 320d SE) I used to regularly go from run-flat standard BMW fit Conti-sport contacts (205/55/16 I think) to Dunlop Winter Sport non run flat tyres. Aside from the obvious changes in tread deformation when cornering (which was horrible on the winters), the non runflats gave a nasty bouncy ride. Basically, the tyre sidewall is part of the suspension and that's what an RFT equipped BMW's suspension is tuned for - change an element in that and it's no longer as designed. I couldn't wait to get the RFTs back on in spring each year.

I currently own another E90, this time a 2010 LCI 320d ED, and that doesn't have RFTs, shunning them for Michelin Energy Saver tyres. This isn't really relevant to the discussion though, because the ED suspension was notoriously bad. I switched to Birds' suspension and kept the Energy Saver non-RFT tyres. It's a vast improvement, but the Birds kit is designed to work with non-RFT low profile 17s and 18s, not my non-RFT balloon profile tyres. I can't help wondering if I could improve the ride and handling further by switching to RFTs to get closer to the sidewall stiffness that the non-RFT larger tyres have....

Hello Rob my 330d has AC Schnitzer springs and shocks and that lot is supposed to sit on Michelin Sports non runflat,,but I am telling you the Run Flat Goodyear F1 Eagle assymetric 3 are excellant and Im saying that after 3 years of said non run flat michelins.

[Swervin_Mervin]

RobM77 said:

On my last E90 (a 2007 320d SE) I used to regularly go from run-flat standard BMW fit Conti-sport contacts (205/55/16 I think) to Dunlop Winter Sport non run flat tyres. Aside from the obvious changes in tread deformation when cornering (which was horrible on the winters), the non runflats gave a nasty bouncy ride. Basically, the tyre sidewall is part of the suspension and that's what an RFT equipped BMW's suspension is tuned for - change an element in that and it's no longer as designed. I couldn't wait to get the RFTs back on in spring each year.

I currently own another E90, this time a 2010 LCI 320d ED, and that doesn't have RFTs, shunning them for Michelin Energy Saver tyres. This isn't really relevant to the discussion though, because the ED suspension was notoriously bad. I switched to Birds' suspension and kept the Energy Saver non-RFT tyres. It's a vast improvement, but the Birds kit is designed to work with non-RFT low profile 17s and 18s, not my non-RFT balloon profile tyres. I can't help wondering if I could improve the ride and handling further by switching to RFTs to get closer to the sidewall stiffness that the non-RFT larger tyres have....

You could just try some better non-RFT tyres than energy saving ones! You can't expect a reasonable comparison between soft winter/energy saving non-RFT to normal/sport oriented RFT tyres

Look for extra load versions of the likes of the Eage F1 or the Michelin PS3

[FurtiveFreddy]

Swervin_Mervin said:

You could just try some better non-RFT tyres than energy saving ones! You can't expect a reasonable comparison between soft winter/energy saving non-RFT to normal/sport oriented RFT tyres

Look for extra load versions of the likes of the Eage F1 or the Michelin PS3

I tend to agree. Apples and oranges...

[RobM77]

Swervin_Mervin said:

RobM77 said:

On my last E90 (a 2007 320d SE) I used to regularly go from run-flat standard BMW fit Conti-sport contacts (205/55/16 I think) to Dunlop Winter Sport non run flat tyres. Aside from the obvious changes in tread deformation when cornering (which was horrible on the winters), the non runflats gave a nasty bouncy ride. Basically, the tyre sidewall is part of the suspension and that's what an RFT equipped BMW's suspension is tuned for - change an element in that and it's no longer as designed. I couldn't wait to get the RFTs back on in spring each year.

I currently own another E90, this time a 2010 LCI 320d ED, and that doesn't have RFTs, shunning them for Michelin Energy Saver tyres. This isn't really relevant to the discussion though, because the ED suspension was notoriously bad. I switched to Birds' suspension and kept the Energy Saver non-RFT tyres. It's a vast improvement, but the Birds kit is designed to work with non-RFT low profile 17s and 18s, not my non-RFT balloon profile tyres. I can't help wondering if I could improve the ride and handling further by switching to RFTs to get closer to the sidewall stiffness that the non-RFT larger tyres have....

You could just try some better non-RFT tyres than energy saving ones! You can't expect a reasonable comparison between soft winter/energy saving non-RFT to normal/sport oriented RFT tyres

Look for extra load versions of the likes of the Eage F1 or the Michelin PS3

Thanks. I like lower grip and find the car progressive enough for me. I’m worried that Eagle F1s will give me too much grip?

[Dino D]

E-bmw said:

Speed addicted said:

I think the wheels for run flat tyres are different, not sure you can just switch to them if it didn’t have them in the first place.

You are right in so much that you can't fit run flats to non-run-flat wheels, you can, however do the reverse.

That’s the case for most RFT up until the DriveGuard:

‘DriveGuard, however, is the first full line of RFT available for coupés, sedans and wagons not originally equipped with run-flat tyres.’

http://www.bridgestone.co.uk/tyre-talk/article/wha...

Must have TPMS though

[anonymous-user]

Dino D said:

That’s the case for most RFT up until the DriveGuard:

‘DriveGuard, however, is the first full line of RFT available for coupés, sedans and wagons not originally equipped with run-flat tyres.’

http://www.bridgestone.co.uk/tyre-talk/article/wha...

Must have TPMS though

Well I wouldn’t bet on that, though it’s not as black and white as some make out.

There’s no such thing as a Runflat wheel. RFTs do need to be fitted to a double hump rim though, H2 and ideally an extended double hump rim, EH2.

BMW have used EH2 rims for years as have other manufacturers. Others use H2. Some use H (single hump)

Aftermarket wheels can be all sorts though more commonly H

[Mr Tidy]

Suitable rims aren't the only issue though.

My 2007 123d and my 2006 Z4 have TPMS based on the ABS sensors I think - newer BMWs rely on the valve stems. I would imagine the warning system needs to be compatible with the components that may detect an issue.