[ChrisMWard]

Originally Posted by the_oracle1980

as a lower inflated tyre/flat tyre turns slower in relation to the other wheels.

Actually a deflated tyre turns faster than the other wheels due to the decreased rolling radius.

Regards

Chris

[red-max]

You might also want to consider what happens when it's time to trade the car in for a new one. If you trade it in to a BMW dealer, he might not be too happy that you've not got RFTs on there - that is if he noticed, perhaps he's more likely to notice if you've got non-OEM rims as well.

One solution for this of course is to keep the original tyres (and wheels) and swap them back on when it's time to trade in. Or sell the car privately. Or trade into an VW/Audi dealer :-o

Insurance is another good question ... personally I'd rather be completely truthful and know I was insured, so you probably should tell your insurance company if you change to a different type of tyre..? Could be bl**dy expensive if you wrote the car off and they refused to pay out.

[NFS]

Originally Posted by gjdavies

What would an insurance company say in the event of a major accident where the cause of the accident or the results were attributed to having the incorrect tyre on the vehicle? Is BMW's recommendation somehting that an insurance company would look at? I think it might be.

For example, several acccident investigations have come to the conclusion that having Non Extra Load tyres caused a blowout. My fleet company made Kwik Fit swap 4 newish tyres for extra loads when they found out for this very reason.

Could the same scenario occur with non run-flats?

This is NOT an issue for non-runflats on BMW's. BMW recommend but do not insist on runflats. There is an obvious and significant difference between the 2

[335iman]

Whats the problem with the run flats. on road grip seems fine to me.
Anybody know any different. Mazda decided against using them on the RX8 & provided you with a puncture repair kit. Having owned a RX8 for 3 years and been on a driver experiance day with Prodrive who helped develope the car for the UK. They said that mazda could not get the performance they required . Have run fats moved on in the past 3 years.

[NFS]

Originally Posted by 335iman

Whats the problem with the run flats. on road grip seems fine to me.
Anybody know any different. Mazda decided against using them on the RX8 & provided you with a puncture repair kit. Having owned a RX8 for 3 years and been on a driver experiance day with Prodrive who helped develope the car for the UK. They said that mazda could not get the performance they required . Have run fats moved on in the past 3 years.

When I had my e60 I spent quite a bit of time at e60.net.

Many people there felt that the runflats seriously degraded performance and ride quality. A large percentage were ditching them for traditional tyres.

In contrast to the e60 the e90 was designed to use runflats from the outset.

The motoring press slammed the runflats on the e60, but rarely got upset with them on the e90.

Having gone from a 530d SE with 19inch trad tyres to a 330i with 18inch runflats I am certain that the e90 grips, rides and handles better.

It may be that it would slightly improve with traditional tyres, but the runflats are not a problem, so I will probably never find out.

[gjdavies]

Originally Posted by needforspeed

This is NOT an issue for non-runflats on BMW's. BMW recommend but do not insist on runflats. There is an obvious and significant difference between the 2

Cool, just floating it out there...........especially after the incident with the incorret load ratings.

[ZiM]

well, i'm feeling a lot better about being on runflats... one of my main concerns about ride quality was the 19s... and when i got worried i tried to change but cuz the car was already at the dealership they wouldn't let me

i'm still of two minds about the 18 vs 19 argument, not just comfort but i'm still undecided as to which one looks better...

[NFS]

Originally Posted by gjdavies

Cool, just floating it out there...........especially after the incident with the incorret load ratings.

So long as the fitment, size and speed ratings match runflats and trad tyres are effectively the same.

It's just that on will 'run flat' and the other will not.

I would agree that substituting a tyre of a lower speed or load rating would be a problem.

I don't see how that could apply in terms of a runflat.