Are 19" wheels and run flats a problem?

B

Breaker

Elite
Is there a potential problem with 19" wheels and run flat tyres?

I saw this on Watchdog last week (in the UK) about 3 Series wheels cracking and one of the suggestions was that the 19" wheels with run flat tyres were the culprit? The theory being that the run flat tyres are too hard in the tyre walls being so low and don't give any cushioning on bumpy pot-holed roads we have in the UK. Interesting watch!

Now, I really like the OEM 19" wheels for the new Z4 and was thinking of getting some next year (mine are the 18", which are growing on me!), but I am having second thoughts now!

http://www.bbc.co.uk/blogs/watchdog/2009/10/bmw_alloy_wheels.html
 
why would you buy runflats anyway, they suck and make the car so much worse to handle. it was my first mod - getting rid of runflats once they were worn out enough.

it's also a bridgestone specific issue I should add. BS admitted it themselves in a letter in BMW Car mag few months ago.
 
Yes, but what if you bought the Z4 with the 19" wheels (new shape has an option of 19" wheels) with run flats? Taking the run-flats off also can have a warranty/insurance problem!
 
I'm still in two minds about no-RFTs. I spoke to two tyre specialists who both said its much more difficult to repair a tyre that had Tyre Weld used on it, and they often have to junk the tyre for a new one.

And Breaker is right....I suspect the insurance thing would be more difficult to prove but I'd be pretty certain that if you went in with a buckled/cracked wheel claim, possibly even suspension for that matter, you'd be struggling for any goodwill.....
 
im probably the only one but i dont have a problem with runflats, if you want a sporty car you have to live with the hard ride, as for the potholed roads well we live in a 3rd world country now so do what i do watch out for them and drive round them. i have tried 2 cars a 3 series and a z4 with non runflats and i find with both the handling is not as sharp and the increase in ride comfort is minimal. the only solution i think is to vote for a change in government and perhaps they will drag us out of the mire.
 
acerboo said:
im probably the only one but i dont have a problem with runflats, if you want a sporty car you have to live with the hard ride, as for the potholed roads well we live in a 3rd world country now so do what i do watch out for them and drive round them. i have tried 2 cars a 3 series and a z4 with non runflats and i find with both the handling is not as sharp and the increase in ride comfort is minimal. the only solution i think is to vote for a change in government and perhaps they will drag us out of the mire.
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You are not the only one...

I did find the bridgestones too hard and crashy though. Michelin run flats are in a different league though.

Pot holes can be avoided given plenty of planning as Im sure any motorcyclist or cyclist will attest to :thumbsup:
 
gannet said:
acerboo said:
im probably the only one but i dont have a problem with runflats, if you want a sporty car you have to live with the hard ride, as for the potholed roads well we live in a 3rd world country now so do what i do watch out for them and drive round them. i have tried 2 cars a 3 series and a z4 with non runflats and i find with both the handling is not as sharp and the increase in ride comfort is minimal. the only solution i think is to vote for a change in government and perhaps they will drag us out of the mire.
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You are not the only one...

I did find the bridgestones too hard and crashy though. Michelin run flats are in a different league though.

Pot holes can be avoided given plenty of planning as Im sure any motorcyclist or cyclist will attest to :thumbsup:
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Being a motorcyclist myself I agree, but you haven't the same amount of room to manoeuvre a car as a motorbike going into a bend! :wink:

This isn't the point though, the wheels should be fit for purpose! Everything made for a car that is a critical item should be engineered impact tested to well above what any owner can do to it on an average drive!
 
lacroupade said:
I'm still in two minds about no-RFTs. I spoke to two tyre specialists who both said its much more difficult to repair a tyre that had Tyre Weld used on it, and they often have to junk the tyre for a new one.

And Breaker is right....I suspect the insurance thing would be more difficult to prove but I'd be pretty certain that if you went in with a buckled/cracked wheel claim, possibly even suspension for that matter, you'd be struggling for any goodwill.....
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But replacement tyres are in the realms of normal money, so you wouldn't even repair a tyre anyway.

RFT doesn't mean invincible, it means you can run on it when flat for about 50 miles to get it fixed, but without being left stranded, you still need to replace it if it has been run on flat for any length of time. So only if the RFT has been run on flat for say 10 urban miles and can be plugged in the centre of the tread area are you ok.

The alternative is to fill your normal cheaper tyre with foam, run on 'inflated', and then do either of the above.


The only benefit of RFT is that you *might* catch it early (monitoring doesn't spot slow punctures so you might not spot it for the time between manual checks with a gauge) and get it plugged.
Downsides are you bin a £200+ tyre and replace with a £200+ tyre, and if it's near half > full worn you need to buy 2 x £200+ tyres.

Or, you just squirt foam in, and have a £75-£100 bill for a front, and £100-£150 bill for a rear, and none of the associated issues with RFT (jittery random lateral movements)


As for insurance, I've not found any insurer that had a problem with non-rft when asked.

BMW really are being retarded in this area. I kinda get them not wanting to lose boot space for spares when it'll reduce boot space vs the fwd Audi etc who don't have to have a rear diff etc, but you have to ask yourself if the buyers that care about boot space volume are really the kinda people that will be faithful to the BMW brand longer term anyway!

Personally I'd rather have a full size spare or a tin of foam, than crappy expensive tyres.

Dave
 
all very true, the other thing that often gets forgotten for me is the infrequency of actually getting punctures in the first place.

40k miles here with only tyre goo to help me out and I've not been stranded. (yet... now I've said it)

Even then there's BMW Assist who I'd try my luck with, if I was bothered about all of these things not coming together I'd have a spare space saver in my garage I could go fetch if needs be.

But having a good ride does matter, every single mile of your journeys.

Breaker - I'd drive one on 19s and see how it felt, I'm not sure why I understand that on a 19" rim where you have no rubber at all to cushion you against a big pothole, what's the difference between RF/Non-RF to protect the rim from damage, surely RF would be stronger so everyone on here with CSLs has a similar problem against UK roads.
 
Surely RF's have stiffer side walls so therefore they wouldn't offer as much (all be small on 19" tyres) cushioning. Also, aren't RF's better in a high speed blow-out on a motorway?

Going back to the Watch dog report, I would guess it's something wrong with the wheels! I hope the same isn't wrong with the new Z4 wheels! Think I'll keep my 18's! :wink:

By the way: http://www.yell.com/motoring/blog/by-2012-we-could-all-be-running-flat/
 
Breaker said:
Surely RF's have stiffer side walls so therefore they wouldn't offer as much (all be small on 19" tyres) cushioning. Also, aren't RF's better in a high speed blow-out on a motorway?

Going back to the Watch dog report, I would guess it's something wrong with the wheels! I hope the same isn't wrong with the new Z4 wheels! Think I'll keep my 18's! :wink:

By the way: http://www.yell.com/motoring/blog/by-2012-we-could-all-be-running-flat/
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I think a consideration is that an RFT simply replaces inflation pressure support with tyre sidewall stiffness support when the inflation pressure is not avaiable.

I've not tested yet, but I wouldn't expect the RFT to be THAT much stiffer than a non-rft when properly inflated.

What IS an issue (I noted after my first few days of ownership), is that the RFT calibration can drift out, and I was running 10-20psi varied around the car upon pickup (apparently after a 200 point check :headbang: ) but I didn't really notice in the sidewall when you looked at the car, nor did it drive hugely differently.
BUT, in those conditions, I bet there is a great deal less cushioning and tyre damping, and the alloy wheel will get a much harder time of things!

So, I wonder, if many of these issues are from people driving on low/flat RFT's on bumpy roads!?

Dave
 
Breaker said:
Yes, but what if you bought the Z4 with the 19" wheels (new shape has an option of 19" wheels) with run flats? Taking the run-flats off also can have a warranty/insurance problem!
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Please explain.......
 
This isnt just a problem with 19" rims, my boss has a 535d M Sport with 18# rims and has had two cracked so far.

The cost of Falken 452's is half of the cost fo a Runflat so if you have to bin after a puncture due to tyre weld your still £300 up over a set of 4, and most garages wont repair RFT's anyway.

The ride is so much better win Non run flats, they actually stick to the road in the wet which helps.

And with regard to insurance companies, there are plenty around that will insure without issue, esure for one, and the boards own insurance company also.

BMW also have no warranty issues with using non RFT's
 
AlanJ said:
Breaker said:
Yes, but what if you bought the Z4 with the 19" wheels (new shape has an option of 19" wheels) with run flats? Taking the run-flats off also can have a warranty/insurance problem!
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Please explain.......
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Some insurance companies do look on RFT's as a safety feature and some don't like it as you have taken off an OEM style fitment. Not all admittedly. Worth checking.

See here: http://www.bmw.co.uk/bmwuk/owner/servicing_programmes/service_products/0,,1312___dht-aHR0cDovL3d3dy5iYXllcmlzY2hlYm13Lm5ld2RvbG4ubmV0,00.html?cnr=3

Now most of the first set of pointed reasons may be marketing hype, but if an insurance company buys it, they won't like you taking them off! :wink:
 
It does say though, that in an emergency if you can't find an RFT replacement, that you can use a non-RFT replacement tyre.

If the manual says it is ok, then insurers might have difficulty refusing a claim if you were following the guidelines in it!

Dave
 
Mr Whippy said:
srhutch said:
BMW also have no warranty issues with using non RFT's
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Well they will have less with non-RFT's anyway :rofl:
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Not quite what I meant but agree, with you.

What I did mean is BMW wont void any of your warranty for running non RFT's
 
non run flats mean you have to live with the following:
1. higher unsprung mass
2. jittery ride
3. only replacement option in case of puncture (if you drove on punctured runflat, contrary to what has been said here, you are not allowed to patch it because the sidewalls have been weakened - now this is an insurance issue because BMW specifically says do no replace and in US those shops that konw about it refuse to patch it!!!)
4. high replacement cost, about 30%
5. Documented and confirmed uneven and faster wear
6. potential suspension issues down the road due to 1&2, more rattles
7. easier to bubble

So why bother? You can believe and pray on BMW technology all you want, but frankly saying "oh it's a sports car it should be hard" just shows your ignorance a bit.

for a fact one could say that with regular tyres you get:
1. better ride
2. better handling
3. cheaper replacement cost
4. insurance is not an issue as long as you get an approval from the dealership - if they say that's ok, go ahead and let your insurance know for a piece of mind. In my experience BMW always say "it's ok".
5. A can of spray that can actually be used to patch up the tyre.

Yes you lose the warning on blow out but then again, usually if you inspect your tyres regularly, and don't exceed their limits - why be worried so much, statistically there are much more dangerous things out there.
 
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