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[j-man]

Ive recently taken delivery of my new 320D SE, just like to ask some questions from a fellow owner.

I have approx 1000 miles on my clock, yet the ride seems to be a bit bouncy, as in the suspension being too firm or possibly from the run flat tyres - it seems as if every stone is felt, maybe Im being too sensitive - any thoughts?

Do you know what the total run in period is?

Please help

[LEDZEP]

Check your tire pressure for one thing. The dealer had mine at 39 psi in the rear. I've been reducing it (so far to 36) and the ride continues to improve. The tires will wear faster also if kept overinflated. The only benefit will be increased mileage.

[CorporalCarrot]

J-Man

Definitely check your tyre pressures. AFAIK most manufacturers inflate tyre pressures up to 35-40 psi during transport (perhaps someone knows why this is). As part of vehicle prep the dealer should put them to the correct pressures (which you will find in your manual) but its something they often forget. When I got my E46 coupe, like Ledzep, the tyre pressures were way too high.

Oh and Ledzep, I thought tyres wore faster when underinflated due to the increased drag and larger contact point with the road?

C

[chrisbin]

J-Man - you have PM.

[nexus66]

Originally Posted by CorporalCarrot

J-Man
Oh and Ledzep, I thought tyres wore faster when underinflated due to the increased drag and larger contact point with the road?
C

When overinflated tyres wear on the centre of the tread, when underinflated they wear on the outer edges (shoulders).

And unfortunately when correctly inflated they wear all over the tread! (Although not as quickly)

[j-man]

Thanks for the feedback, it just seems that the ride is a bit bouncy at times. I have the standard 16" wheels, and standard suspension. Could it have anything to do with DTC ( Dynamic Traction Control)or DSC - stability control??
I will re-assess tomorrow whilst driving, perhaps it was just particular road conditions etc when I formed the opinion.

[PhilS]

Originally Posted by CorporalCarrot

J-Man

Definitely check your tyre pressures. AFAIK most manufacturers inflate tyre pressures up to 35-40 psi during transport (perhaps someone knows why this is).

C

I think the manufacturers do this to prevent flat spots forming on the tyres if they are parked in storage for a prolonged period of time.

[BM Bridger]

I've been driving my 320d SE since mid-April and agree that the ride, whilst not being bad, can best be described as "fidgety" and never really settles down or relaxes. This is especially noticeable at speed, when going over small bumps or changes in road surface.

In my humble opinion this is down to the runflats. I tried swapping with a set of standard E46 16inch wheels with "normal" tyres from a friends car, but unfortunately the E46 wheels foul the front brake discs on the E90 so I wasn't able to conduct a test drive.

Needless to say that when the runflats wear out they will not be replaced by more runflats; irrespective of what BMW say about the suspension being tuned for runflats.

Another thing that was really obvious when changing the wheels was the weight of the runflats compared with the normal tyres - they weigh a LOT more! I was brought up to believe that reducing un-sprung mass was always the goal - not increasing it. Runflats also seem to negate the basic idea of a pneumatic tyre. Perhaps BMW should fit solid tyres as the next "safety" innovation!

You have probably gathered by now that I am not a great fan of runflat tyres.

Anyhow, apart from the fidgety ride - which I'm hopeful can be cured by fitting normal tyres, the E90 320d is a great car to own and drive (oh, and also apart from the dreadful Vauxhall Vectra styled turn indicator control!!)

BM Bridger

[j-man]

Any thoughts on where to keep the spare tyre

[BM Bridger]

Probably have to lash a spacesaver in the boot. Not very elegant I know. Alternatively, a can or 2 of emergency tyre weld, although I am not entirely sure of the legal requirements in the UK.

Anyhow, where there's a will, there's a way!

[j-man]

Anyone else thinking of changing from run flats to normal tyres?

[thebigman]

I think the weight issue is irrelevant, losing the spare more than makes up for the additional weight of the run-flats, IMHO.

Ultimately, I think the ride is down to the quality of the road surface, and in the UK generally, it is appalling. Take a trip to Europe (France, Germany, et al.) and you probably will find the ride near perfect.

There is a great deal of competition between all the manufactures brewing and this can only improve the quality of the tyres.

From a safety perspective, I think these tyres are a huge step forward.

[stressdoc]

The issue with the runflat weight is where the weight is: unsprung, vs. the spare tire in the trunk as sprung weight. By analogy, wearing 10 kilo boots is more tiring than a 20 Kilo waistpack. But it turns out the difference btw same size&brand runflat and regular is 3 lbs. Significant if you are off road racing, but not a big deal on a luxury street car.

[j-man]

thanks for the info guys

[ivanwibi]

I read in a few motoring magazine that the high tyre pressure is to ensure that the car does move around very much whilst shipping (due to rocking motion on the sea).The cars are tied down on both ends using chains, without the stuffing of highly inflated tyres in between you can image that some cars will be free to jump around.

Hence they even put up the tyre pressure.

[sysop]

Originally Posted by BM Bridger

I've been driving my 320d SE since mid-April and agree that the ride, whilst not being bad, can best be described as "fidgety" and never really settles down or relaxes. This is especially noticeable at speed, when going over small bumps or changes in road surface.

In my humble opinion this is down to the runflats. I tried swapping with a set of standard E46 16inch wheels with "normal" tyres from a friends car, but unfortunately the E46 wheels foul the front brake discs on the E90 so I wasn't able to conduct a test drive.

Needless to say that when the runflats wear out they will not be replaced by more runflats; irrespective of what BMW say about the suspension being tuned for runflats.

Another thing that was really obvious when changing the wheels was the weight of the runflats compared with the normal tyres - they weigh a LOT more! I was brought up to believe that reducing un-sprung mass was always the goal - not increasing it. Runflats also seem to negate the basic idea of a pneumatic tyre. Perhaps BMW should fit solid tyres as the next "safety" innovation!

You have probably gathered by now that I am not a great fan of runflat tyres.

Anyhow, apart from the fidgety ride - which I'm hopeful can be cured by fitting normal tyres, the E90 320d is a great car to own and drive (oh, and also apart from the dreadful Vauxhall Vectra styled turn indicator control!!)

BM Bridger

I totally agree with you about the ride. I did in fact try swapping with E46 wheels (same size) and found them much better but unfortunately was only able to try them round town and not on a trip. They were much better, it seemed.

[sysop]

Originally Posted by j-man

Ive recently taken delivery of my new 320D SE, just like to ask some questions from a fellow owner.

I have approx 1000 miles on my clock, yet the ride seems to be a bit bouncy, as in the suspension being too firm or possibly from the run flat tyres - it seems as if every stone is felt, maybe Im being too sensitive - any thoughts?

Do you know what the total run in period is?

Please help

Agreed, I am not impressed with the "springing". Preferred that of the E46.