[HighlandPete]

Originally Posted by Mixter

Reading this makes me think I need to get some this year then as opposed to leaving the car on the drive for 2 weeks. I have never been convinced they make they much of a difference but you lot are convincing me otherwise!

Think in terms of cold weather as well. I'm off out in a few minutes, road is damp but under freezing point at present, so there will be ice pockets. Much greater safety factor for stopping and controlling the car.

As a side note the winter run-flats are softer than the summer tyres at colder temperatures so a better ride as well. I run 18" wheels in the summer, 17" in the winter.

HighlandPete

[rich1068]

Not often on here because err... I haven't got a 5er.

But keeping in mind the title of this thread particularly "(with no changing wheels)"...

Originally Posted by remmib

My concern is the tyres that you have to put on an off the wheels two times a year, but sure if they can be damaged.

On my E91 running 18s I fully intended to just have the tyres swapped and use the same wheels. I got hold hold of some Contis and had the summer run flats taken off in November 2011. However, when I returned in the new year to have the run flats put back on the fitter warned me that the machines can cause considerable damage to the runflat sidewall. Run flats are just not designed to be taken off, put back on, taken off etc etc.

He had no motive for telling me this other than being helpful and I also heard this from another fitter at another tyre outlet.

[Mixter]

Interestingly that was going to be my next question - is there a possibility of tyre damage on removal?

[rich1068]

I'm no expert on tyre construction but from what I understood the inside of the stiffened sidewall can be gouged by the machine as the tyre is removed. Normal tyres give but run flats don't.

It makes sense as the official line on run flats is that if it's punctured you get to where you need to be and then throw it away.

[HighlandPete]

Originally Posted by rich1068

...However, when I returned in the new year to have the run flats put back on the fitter warned me that the machines can cause considerable damage to the runflat sidewall. Run flats are just not designed to be taken off, put back on, taken off etc etc.

He had no motive for telling me this other than being helpful and I also heard this from another fitter at another tyre outlet.

That is the issue, echoed by many tire shops.

It is a pretty brutal procedure, even with the correct equipment and training. The problem, like running on the tires when flat, and getting a repair, you can't necessarily see the damage. Removal and remounting could do damage and you won't know if the structure has been compromised. The risk factor is increased for future tire failure.

I'd certainly not be tempted to remount run-flat tires on a seasonal basis.

I wouldn't even do it with normal tires, let alone with run-flats. Plus with dedicated wheels you have the chance to have a decent summer wheel set and an appropriate wheel set for winter driving. For example, a smaller winter rim allows a higher aspect ratio and a narrow tire section for optimum winter performance.

HighlandPete

[73henny]

Originally Posted by HighlandPete

That is the issue, echoed by many tire shops.

It is a pretty brutal procedure, even with the correct equipment and training. The problem, like running on the tires when flat, and getting a repair, you can't necessarily see the damage. Removal and remounting could do damage and you won't know if the structure has been compromised. The risk factor is increased for future tire failure.

I'd certainly not be tempted to remount run-flat tires on a seasonal basis.

I wouldn't even do it with normal tires, let alone with run-flats. Plus with dedicated wheels you have the chance to have a decent summer wheel set and an appropriate wheel set for winter driving. For example, a smaller winter rim allows a higher aspect ratio and a narrow tire section for optimum winter performance.

HighlandPete

Must admit, I don't really get this changing wheels to a smaller winter set up. We spec the cars with the wheels we want, so why for 25% of the year would you want smaller rims that don't look as good?

[HighlandPete]

Originally Posted by 73henny

Must admit, I don't really get this changing wheels to a smaller winter set up. We spec the cars with the wheels we want, so why for 25% of the year would you want smaller rims that don't look as good?

I come from the 'form over fashion' side of wheel choice. I don't choose to compromise ride and handling, on our typical UK roads, to have fashionable over-sized rims.

It is a big subject and often debated. Autocar posted a blog after Steve Sutcliffe found a BMW 1M coupe worked far better on 18" wheels, rather than the 19" from BMW, to see where users put their priorities. Fashion, even with driving compromises, appeared to come first, rather than driving performance. Many willingly endure a worse handling car with poor ride quality just to have a look.

I don't personally don't get how users will rather have a look, than optimum tyre performance and the highest degree of safety in all conditions. Perhaps I'm from a dying breed.... maybe.

I know there are quite a few motoring journalists/writers who think wheel sizing is getting out of hand, right across the motoring industry, for many reasons. Includes costs, ride, noise, poor chassis dynamics, and it is time to get back to the basics of what wheels and suspension are supposed to do.

HighlandPete