Change run-flats to standard tyres?

GolfBravo

Nearly_Old wrote: »

As for tyre pressures they can vary greatly between different tyres even of the same type. I've got 2 sets of wheels for the Z3 and the Goodyear Eagle F1's are best at 31Fr 33Rr whilst the Falken 912's are better at 32Fr 35Rr.

31PSI front? That sounds really low (only about 2.1 bar) - is that the recommended pressure for this particular tyre's load? What do the tyre placard and tyre specs indicate?

And why would you have lower pressure at the front? Is your car's rear heavier than front?

neilmcl

GolfBravo wrote: »

31PSI front? That sounds really low (only about 2.1 bar) - is that the recommended pressure for this particular tyre's load? What do the tyre placard and tyre specs indicate?

And why would you have lower pressure at the front? Is your car's rear heavier than front?

Quite normal for BMWs, don't forget they're RWD as well as a lot of them with 17" wheels and above have staggered sizes. For example. the recommended pressures for mine is 2.1 bar Front, 2.3 bar Rear. Now that I've got non-RFT 16" winters on I've set them to 34psi all round.

sunshinetours

There are some indisputable benefits to run flats, however there are some major drawbacks aswell, especially on cars that are directly marketed as being drivers cars.
Pandering to the US amrket as said before has hurt their image with many die hard BMW fans and I wouldn't have chosen a model fitted with run flats, having driven some. My winter tyres sadly are run flats and although grip levels are Ok for winter tyres and they do the job they need to, I will be changing all 4 next year to non run flat winters once treads have worn down to about 4/5mm

sunshinetours

GolfBravo wrote: »

31PSI front? That sounds really low (only about 2.1 bar) - is that the recommended pressure for this particular tyre's load? What do the tyre placard and tyre specs indicate?

And why would you have lower pressure at the front? Is your car's rear heavier than front?

Mine is on a staggered set up and the rears are always higher pressure than the front (per the door placard)

Beastface

Thanks for the responses everyone.

The car went in for a service today and I've been told that whilst there is 5mm left on the fronts in the centre of the tyres, the outer edges of the current run flats have worn down almost to zero. I've had a read online and it seems like this is common with the Bridgestone Potenza run flats fitted as standard.

So this has somewhat tipped my hand - £500 for two replacement run-flats or £475 for 4 corners of Falken 452s which seem to be highly recommended by lots of people who have made the same move on BMW forums.

Insurance company have noted the change but no impact to premium. Looking forward to getting them on and seeing what difference it makes to the drive - people suggest less tramlining, greater ride comfort, better handling, and reduced road noise after making the change.

Oh and they are 18" Style 193 BMW alloys on a 2009 325D M Sport for anyone who is interested.

andygb

Beastface wrote: »

Thanks for the responses everyone.

The car went in for a service today and I've been told that whilst there is 5mm left on the fronts in the centre of the tyres, the outer edges of the current run flats have worn down almost to zero. I've had a read online and it seems like this is common with the Bridgestone Potenza run flats fitted as standard.

So this has somewhat tipped my hand - £500 for two replacement run-flats or £475 for 4 corners of Falken 452s which seem to be highly recommended by lots of people who have made the same move on BMW forums.

Insurance company have noted the change but no impact to premium. Looking forward to getting them on and seeing what difference it makes to the drive - people suggest less tramlining, greater ride comfort, better handling, and reduced road noise after making the change.

Oh and they are 18" Style 193 BMW alloys on a 2009 325D M Sport for anyone who is interested.

I would agree with all those comments, and add that the run flat tyres on my BMW were changed after wearing unevenly after 15K miles. The replacement standard tyres lasted 25K, were cheaper and had even tread wear.

Nearly_Old

GolfBravo wrote: »

31PSI front? That sounds really low (only about 2.1 bar) - is that the recommended pressure for this particular tyre's load? What do the tyre placard and tyre specs indicate?

And why would you have lower pressure at the front? Is your car's rear heavier than front?

As others have confirmed with staggered wheels and RWD it is normal to have a higher pressure in the rear tyres.

As for the actual pressures used this can vary on how you want the car "setup" as again everything is a compromise. I start with the recommended pressures and then take the car out a few times on one of my local runs. If necessary I will trade comfort & tyre wear for a more precise turn into corners together with the ability to get the power back on again as quickly as possible. Not very MSE but I've got a diesel for everyday journeys and the other cars were bought for fun - especially on twisty roads.

tytomaen

Try promotive they are a BMW specialist and are advertising runflat tyres on their website, regards ttm

red_eye

BAA1 wrote: »

A company like BMW spend millions on car development and design, which includes suspension set-up in conjunction with wheel / tyre specifications.

BMW have specifications for the type of tyre that can / should be fitted to each model, and also which tyre combination is suitable for each car's suspension characteristics.

But, if you guys think you know more than the BMW designers, then go for it :rotfl:

Oh, and just because a dealer recommends non-run-flat Winter tyres, does not mean that those will be the best match for your car's suspension. The majority of dealer salespeople have little or no technical knowledge, so unless they ask the relevant technician for the correct tyre specifications, I would take what they say with a pinch of salt.
The key is : Only fit tyres that are listed by the manufacturer for your particular car. (So if they do list non-run-flats, use that listed spec of tyre if you wish)

there is not much difference in suspension. running normal tyres on run flat suspension will make the ride a little softer that's all. after all its only a few lbs added to the standed spring rate