xDrive pretty good - RFT's diabolical

[gizlaroc]

numtumfutunch said:

Wills2 said:

tjlees said:

AWD only gives traction and not grip!

This, I think the OP has just realised that getting going doesn't mean you'll be able to stop and steer.

I'm amazed people don't understand these simple concepts.

You didnt read the whole thread did you?

Ive just ben out again in heavy snow and once again the car can climb surprising gradients but is utterly useless on the brakes

I ran a RWD 330 for several winters pre runflats and it was nowhere near as bad as this hence my question about how much the RFT's are responsible for its lack of ability

Cheers

I think you have missed what they have said, what they said is exactly what you are experiencing, you will get traction (moving) but you will have no grip (stopping). The heavier the car the worse this will be, the wider the tyres the worse this will be.

The tyre pattern will make more difference then whether they are run flats or not, quite simply the combo of summer tyre on heavy truck and wide wheels is not going to be anything other than dangerous in the snow.

If you can't stop normally you should stop using it before you do some real damage or kill someone, or get some winter tyres on it.

[msej449]

numtumfutunch said:

Ive just been out again in heavy snow and once again the car can climb surprising gradients, but is utterly useless on the brakes. I ran a RWD 330 for several winters pre runflats and it was nowhere near as bad as this hence my question about how much the RFT's are responsible for its lack of ability.

So just to reiterate - runflats vs non-runflats are entirely irrelevant to snow traction. Here is a chart that may help position the various options that do affect snow handling. Ranges from warm+dry summer on the left, through cold+wet winter in the middle, to snow on the right.



And if you compare your summer tyres to my winters just in terms of the tread pattern:



I would think that my winters are a lot 'chunkier' and will grip the snow far better, and that's before any benefits from softer tread compound, higher sipe density or narrower width come into play.

{The 'gap' thing in the diagram was part of a thread on a BMW M Performance forum - I was arguing that BMW 'M' owners should get winter tyres by default, even if they never use the car in snow as winters give them much better traction even in 'ordinary' UK winter conditions of wet and cold. People were posting their DSC was 'lighting up like a Christmas Tree' and this was a problem with their M135i/M140i when really, they just needed to change tyres.}

Edited by msej449 on Sunday 21st January 12:29

[MarkJS]

msej449 said:

So just to reiterate - runflats vs non-runflats are entirely irrelevant to snow traction. Here is a chart that may help position the various options that do affect snow handling. Ranges from warm+dry summer on the left, through cold+wet winter in the middle, to snow on the right.



And if you compare your summer tyres to my winters just in terms of the tread pattern:



I would think that my winters are a lot 'chunkier' and will grip the snow far better, and that's before any benefits from softer tread compound, higher sipe density or narrower width come into play.

{The 'gap' thing in the diagram was part of a thread on a BMW M Performance forum - I was arguing that BMW 'M' owners should get winter tyres by default, even if they never use the car in snow as winters give them much better traction even in 'ordinary' UK winter conditions of wet and cold. People were posting their DSC was 'lighting up like a Christmas Tree' and this was a problem with their M135i/M140i when really, they just needed to change tyres.}

Edited by msej449 on Sunday 21st January 12:29

I can't completely agree with this. I run a E92 320d M Sport which normally runs 19" wheels/tyres staggered with 255's on the rear (run flat). In the winter I have a 17" rim all round with 225 Bridgestone Blizzak LM25's on each wheel. These winter tyres do very, very well in snow when we have it, but on a usual British winter day/night when roads are perpetually damp with temperatures between 1c & 6c, the car can be an absolute handful as they just don't deal with damp, greasy, non-freezing conditions. Could just be that particular tyre, but I really don't think a winter setup is worthwhile in the UK based on my experience.

[anonymous-user]

MarkJS said:

I can't completely agree with this. I run a E92 320d M Sport which normally runs 19" wheels/tyres staggered with 255's on the rear (run flat). In the winter I have a 17" rim all round with 225 Bridgestone Blizzak LM25's on each wheel. These winter tyres do very, very well in snow when we have it, but on a usual British winter day/night when roads are perpetually damp with temperatures between 1c & 6c, the car can be an absolute handful as they just don't deal with damp, greasy, non-freezing conditions. Could just be that particular tyre, but I really don't think a winter setup is worthwhile in the UK based on my experience.

Could well be the tyres. Autoexpress did a wide ranging review of Winter Tyres and they reached a similar conclusion to you. The Blizzak was OK in snow and deep water but not so good in other conditions compared to the others.

I had 4 winters on a set of 17” Sottozeros, RFT, with never a moment’s concern, they were streets better than the 18” Pirelli summer set over the winter.

[msej449]

Yes. If you have a performance car you'll find a lot of variation between different brands of winters, leading to a lot of discussion between owners about which is best. Pirelli Winter Sottozero Serie-II is a particularly good performance car tyre in wet and cold, and occasional snow. But if you are likely to encounter snow regularly, then you might trade some of the wet-weather handling for the better snow traction of the Pirelli Winter Sottozero S3. Choose the right winter tyre and you'll be much happier in winter wet and slippery conditions than any summers. Unfortunately, it's quite hard to identify which particular brands are just right. You see a lot of posts from BMW M Performance owners who've switched to winters and been disappointed: it's only after a while that you start to see a pattern emerging that certain ones disappoint - especially where the owner's chosen one that worked well for them on a previous car, but isn't ideal for their current one.

Edited by msej449 on Monday 22 January 11:18

[gizlaroc]

Blizzaks are crap on anything but snow, try a Vredestein Wintrac Extreme S for a more all round winter.

In fact I have been happy to leave them on all your round on things like Mercs.