2WD is better in the snow than 4WD - what ?!

[nickfrog]

Yes it's all about the contact patch and 4wd is the cherry on the cake if you don't mind carrying it all year round.

4wd can't create friction where it's not there in the first place. And it doesn't work when off the throttle either which is really when you need grip for safety.

[GravelBen]

RobM77 said:

Search on You Tube too - there's a video of a 4x4 on summer tyres sat with all four wheels spinning and a 2WD BMW just driving off - they repeat the test several times.

If you're thinking of the Forester vs M3 video that gets posted up here from time to time then IIRC that Forester isn't just on normal 'summer' tyres, its on worn semi-slicks. I guess its one way to ensure the 'test' gets the result they want.

Edited by GravelBen on Thursday 23 February 19:46

[GravelBen]

nickfrog said:

4wd can't create friction where it's not there in the first place. And it doesn't work when off the throttle either which is really when you need grip for safety.

Off-throttle behaviour depends on the system - with lockable diffs or some LSDs the torque transfer through the drivetrain still happens under deceleration, which helps resist wheel locking.

If you've ever done any off-road driving you would probably have experienced the difference between engine-braking down a steep slippery hill in 2wd vs 4wd.

I agree that the most obvious advantage of 4wd is traction under acceleration though.

[TooMany2cvs]

GravelBen said:

If you've ever done any off-road driving you would probably have experienced the difference between engine-braking down a steep slippery hill in 2wd vs 4wd.

Which is really the same difference as traction - 2wd, you have the forces trying to pull you downhill being held back by the drivetrain through just two contact patches, 4wd you have four.

[shake n bake]

Something something MX-5?

[RobM77]

GravelBen said:

RobM77 said:

Search on You Tube too - there's a video of a 4x4 on summer tyres sat with all four wheels spinning and a 2WD BMW just driving off - they repeat the test several times.

If you're thinking of the Forester vs M3 video that gets posted up here from time to time then IIRC that Forester isn't just on normal 'summer' tyres, its on worn semi-slicks. I guess its one way to ensure the 'test' gets the result they want.

Edited by GravelBen on Thursday 23 February 19:46

Ah, I didn't realise. That was pretty much my experience with 4WD though on summers and 2WD on winters.

[nickfrog]

GravelBen said:

Off-throttle behaviour depends on the system - with lockable diffs or some LSDs the torque transfer through the drivetrain still happens under deceleration

True, forgot that bit - the LSDs in particular have differing % whether under braking or in the traction zone.

[Onehp]

TooMany2cvs said:

That makes me raise my eyebrows...

I wouldn't even have thought they were close. Think about all the 4wd pickups and the like that GM, Ford, Toyota sell in the states. They must surely massively outnumber X5/3/1s...

Point taken, had a search but couldn't find the source. Statememt may be missing a key word, biggest 'premium' manufacturer, however that is defined. Point being not that BMW is biggest, but being very far from 'not a 4wd manufacturer'.

TooMany2cvs said:

... and the relatively few x-drive series.

Point not taken, had a quick count on the german website, forgive me if I miscounted a few up or down, but *not* counting the X_ SUV range, BMW offers xdrive in its regular range of body and engine combinations on... 83 models!! With some exceptions on the smallest models and a few base engines, almost every body style and engine combination is offered with xdrive, on the biggest engines (except non X_ M models) xdrive is the only option. Roughly half of the (extensive) model range is xdrive basically... And they sell a lot of them.

Edited by Onehp on Friday 24th February 01:22

[fttm]

We cope with temps from plus (just) down to minus 45 and plenty of snow and ice . Our dailies are a Ford F150 on all seasons and 150kgs of water softner bagged salt in the bed , used 4wd once this winter reversing up into a parking spot on ice , rest of the time it's traction control and no issues .The other , Jeep GC again on all seasons , goes and stops anywhere and everywhere , great AWD system.
Put a set of winters on my Subaru after Xmas for my kid to drive , said he noticed the difference , going from slicks and coilovers you probably would notice a change

[Cold]

It's worth pointing out that the snowfall in the Alps and other consistently cold places offers a lot more grip than the snowfall we tend to get in the UK. Yes, that does smack of "the wrong type of snow" but UK snow is very wet and not particularly grippy.

[fttm]

Cold said:

It's worth pointing out that the snowfall in the Alps and other consistently cold places offers a lot more grip than the snowfall we tend to get in the UK. Yes, that does smack of "the wrong type of snow" but UK snow is very wet and not particularly grippy.

This is very true , well worth a mention . We can't make snowballs because it's so powdery , and ice at minus 40 offers a surprising amount of grip . As you were

[OldGermanHeaps]

Just be glad that the seller clearly identified himself to you as a lunatic before you wasted time and energy going to view his car.

[so called]

Griffithy said:

I am off to get the RWD TVR
to pull the Defender out of the mud.

Which one?

[anonymous-user]

It's only in the U.K. where you need a Land Rover with a winch, knobbly tyres and 'one life' sticker to cope with the demands of the snow drifts in the South East

[GravelBen]

RobM77 said:

GravelBen said:

RobM77 said:

Search on You Tube too - there's a video of a 4x4 on summer tyres sat with all four wheels spinning and a 2WD BMW just driving off - they repeat the test several times.

If you're thinking of the Forester vs M3 video that gets posted up here from time to time then IIRC that Forester isn't just on normal 'summer' tyres, its on worn semi-slicks. I guess its one way to ensure the 'test' gets the result they want.

Ah, I didn't realise. That was pretty much my experience with 4WD though on summers and 2WD on winters.

I imagine the GT4 tyres were something relatively sporty in nature? I think there is often more difference with sporty tyres than all-round touring tyres - I'm running 205/55-16 touring type tyres on the Legacy these days (mostly for a bit more sidewall height and compliance on gravel) and they have more grip on snow than the 215/45-17 Bridgestone RE002 I used previously.

I'm sure winter tyres are still better, just that there would be less of a difference in that comparison.

[TooMany2cvs]

Onehp said:

TooMany2cvs said:

... and the relatively few x-drive series.

Point not taken, had a quick count on the german website, forgive me if I miscounted a few up or down, but *not* counting the X_ SUV range, BMW offers xdrive in its regular range of body and engine combinations on... 83 models!! With some exceptions on the smallest models and a few base engines, almost every body style and engine combination is offered with xdrive, on the biggest engines (except non X_ M models) xdrive is the only option. Roughly half of the (extensive) model range is xdrive basically... And they sell a lot of them.

They're offered across the range, yes.
But how many do they actually sell? 25%?

[PowerslideSWE]

CABC said:

Do studs normally get fitted to siped tyres? Do some Nordic drivers have 3 tyres? Studded, winter & summer?

There are studded siped ones yes, and I doubt that ppl have 3 sets of tyres. I have a set of summers and a set of studless nordic winters of a questionable brand on my BMW, and in all fairness they are rubbish even in the relatively snow free winters in southern Sweden, the only reason I still have them is because they came with the car. A set of good new studless winters are fab on wet tarmac in cold conditions and to some extent on snow, but they don't have a prayer on a good set of studded ones when there is ice on the roads.

Studded tires makes more of a racket while driving on tarmac though, for obvious reasons.

I don't know if studs are legal in the UK, i know that you are not allowed to drive on studs in Germany anyway.

[TooMany2cvs]

PowerslideSWE said:

I don't know if studs are legal in the UK

They aren't.

[GravelBen]

nickfrog said:

GravelBen said:

Off-throttle behaviour depends on the system - with lockable diffs or some LSDs the torque transfer through the drivetrain still happens under deceleration

True, forgot that bit - the LSDs in particular have differing % whether under braking or in the traction zone.

On loose bumpy downhills (like corrugated gravel roads) I notice a big difference in stability switching between Rwd, open-centre 4wd and locked-centre 4wd in my Terrano - locking the centre really does stabilise the vehicle and help avoid the rear end bouncing off line while braking. It is a different situation to be fair, just an example of how 4wd can improve handling and off throttle behaviour in some situations as well as traction.

Not suggesting everyone needs it because lets be honest, most people don't spend much time doing that sort of driving.

[SimonTheSailor]

OldGermanHeaps said:

Just be glad that the seller clearly identified himself to you as a lunatic before you wasted time and energy going to view his car.

I was going to wait for some snow to fall before viewing the vehicle but I think I missed the end of the auction......