The Accidental Smallholder Forum

Smallholding => Equipment => Topic started by: Womble on March 10, 2018, 11:53:35 am

Title: Driving a 4x4 in snow
Post by: Womble on March 10, 2018, 11:53:35 am

So, this morning I had to drive across a snowy field to collect the trailer. I engaged the low box and diff lock, and set off slowly, aiming to neither spin the wheels nor stall. However, everything went really juddery, with the wheels appearing to stick and slip repeatedly. On occasion, I lost all traction and was spinning two wheels at once, so had to go back a bit and try again (this of course got even worse once the trailer was coupled, and TBH I think I was pretty lucky not to get stuck completely at one point, even though that's really not a huge depth of snow).


On looking at the tracks I left (pictured), it seems that the tyres were gripping the snow ok, but were then shearing that snow off in chunks and throwing it behind. At the points where I had been unable to move, it seems that the snow had not sheared off at all, but had just become a compacted slippery patch, which the wheels then skidded on.


So, help me learn folks. How could I have done this better?
Title: Re: Driving 4x4 in snow
Post by: Womble on March 10, 2018, 11:54:02 am
Oh, I should add that a complete stranger came up to me in a car park the other day to tell me that I had the wrong tyres on for winter weather: "big fat tyres are no use at all. You want nice thin ones that will dig down to the tarmac, you do".  I did try to point out that nice thin tyres will also dig down into muddy fields until I am buried up the axles (don't ask how I found that out), but..... :-\
Title: Re: Driving a 4x4 in snow
Post by: pgkevet on March 10, 2018, 09:54:42 pm
I don't think there are any good answers because snow types and the undersurface can be so variable. I was messing about on the quad bike in 4wd in snow across the fields to give the dog a run and that varied from going ok to getting stuk in deeper stuff and having to back out or back and ram forward and would happily slide sideways on some turns when there was ice below the snow later.

On snowy/icy roads I've had the tractor just slide - when there's no grip there's no grip. The  X-trail does a lot better if driven as you did but that'll slew about on really icy surfaces too. My 2WD fancy sports GT86 with a 'snow' button is totally useless... ended up having to abandon that. That's the only car that's ever let me down. My old nissan 200sx automatic with no fancy electronics copes a heck of a lot better. The ony other trick i know is to load the car with weight. I once went for a fun drive in snow in a v8 rear wheel drive rover SDI and preloaded the boot with 500Kg of cat litter (20 25kg sacks) - now that did go where ohers cars were having problems - mind you f I'd lost the back end ......

Switching off traction control and ABS would probably help.. must most cars don't actually switch them off. In my GT86 it tells you you've switched it off but it's still active as soon as you get to a few MPH unless you pull relays.
Title: Re: Driving a 4x4 in snow
Post by: Maysie on March 12, 2018, 01:14:55 pm
Different tyres types will help for different surfaces, but finding one which does everything is impossible! 

Snow
Mud
Warm Tarmac
Cold Tarmac
Surface water

...they all have different tyre demands, but none of them can beat the laws of physics. 
Title: Re: Driving a 4x4 in snow
Post by: mab on March 12, 2018, 07:44:41 pm
As others have said, there's no single way that's right for all conditions - if you find a technique that works for the conditions then stick with it.

The only observation i have on what you did is that you engaged low ratio - if your 4x4 allows it you're probably better off selecting 4wd high ratio as low ratio 1st is more likely to induce wheelspin - if you have to use low ratio for 4wd then consider starting off in 2nd gear.

As for your choice of tyres - well mud tyres are usually described as 'mud and snow' (labelled on the tyre as M+S) as deep mud and snow have similar tyre requirements:- an open tread pattern with non parallel sides so the mud/snow doesn't stick in the tread and turn the tyre into a 'slick'. looking at your tread patterns in the snow suggest it's a mud & snow tread to me, maybe. Assuming you spend a lot of the year driving on mud rather than snow then M+S or all-terrains are reasonable choices.

As for narrow verses fat - well fat is definitely better on mud and off road - and therefore by implication on soft snow. The only situation where I can see narrow tyres being better is on-road if the snow is close to melting, where the higher ground pressure may splurge the slush/snow out of the way and get your tyre in contact with the road surface - but you could still achieve that by doing what pgkevet did with his SD1 (or by over-inflating your tyres to reduce their footprint). If you're driving on road where you may encounter packed snow/ice as well as new snow then a winter tyre tread would be better  but winter tyres are not so good when there's no snow or ice (too soft - wear out very quickly) so unless you're going to swap them everytime the weather changes...

This year I've put some 'all season' tyres on my 2wd Astra - they do seem quite a bit better on snow/ice (and mud) than normal (summer) tyres and, in theory, should still last reasonably well over the summer - but for a 4x4 which is regularly off-road in mud, a regular M+S/all-terrain might still be the best bet.
Title: Re: Driving a 4x4 in snow
Post by: Foobar on March 14, 2018, 09:44:11 am
but winter tyres are not so good when there's no snow or ice (too soft - wear out very quickly)
but they are better than normals in low temperatures, you will get better grip in general.


That's the trouble with the UK climate, we don't get a proper winter anymore so you can't really justify having two sets of tyres.
Title: Re: Driving a 4x4 in snow
Post by: Magwych on March 14, 2018, 04:29:29 pm
A thought on the diff-lock: I assme that this is on the centre-diff? By engaging it both axles are locked into rotating at the same speed. Once the vehcile strats turning, the axles follow different paths, in order to keep them in synch one or more wheels must skid. If this is not possible you will get what is referred to as "wind-up"; the transmission will lock up, until there is sufficient force to break wheel traction or somethig breaks - like a driveshaft. This could be what you were experiencing.

Better may be to engage 4wd HI, and to leave the diff-lock off.
Title: Re: Driving a 4x4 in snow
Post by: oor wullie on March 15, 2018, 10:00:42 am
Winter tyres give better grip in temperatures of below about 7C regardless of whether there is snow or not.  When it comes to driving on snow they make a massive difference and I have no sympathy at all for anyone who gets in difficulty in winter conditions who isn't using them in my part of the world (Highlands). 

I think the problem with fat tyres is we tend to associate them with the low profile tyres that people fit to their Range Rover Sport, you might as well fix tea trays to your wheels.

Womble.  You say that with the diff lock engaged you had 2 wheels spinning.  Surely the diff lock should ensure all the wheels turn at the same speed regardless of grip?  Or is it a rear diff lock and it was the 2 rear wheels that span together?  If it was 2  wheels on one side spinning then something doesn't sound right.

I also would have used low ratio - better to have the wheels turning slowly but steadily.

Sometimes you just can't win.  This year we have had thick ice on our road for weeks at a time and snow chains on the 4x4 were the only way to get about, even the tractor was totally useless in those conditions.

If however, you have money to burn there is a company that will build tracks for your vehicle.   For many years there was a yellow landrover with tracks sitting at the Lix Toll Garage (near Killin) - Just googled it and they have a picture on their website.  That would solve your problem!!
Title: Re: Driving a 4x4 in snow
Post by: Womble on March 15, 2018, 05:40:41 pm
Thanks for the helpful responses folks.

Re the diff lock question, I'm no expert, but it's just a standard Defender, with a standard Defender diff.

My understanding is that although it's 4wd, there is a differential in between the two axles, as well as between the left and right wheels (so you can go round corners). So without diff lock engaged, if you put one wheel on a frictionless surface and the other three on tarmac, all the power will go to the frictionless wheel, and you'll go nowhere.

I also believe that the diff lock locks the differential between the front and rear axles, so there is always power going to both the front and back axles. However, you can still spin two wheels at once, especially on opposite corners.

That's my understanding anyway, and it does seem to be how my Landy works. If I'm wrong though, (or if it's knackered), could somebody please tell me!?  :o
Title: Re: Driving a 4x4 in snow
Post by: stufe35 on March 15, 2018, 10:55:41 pm
You are absolutely right.

They way I would have driven in those conditions would have been to engage low range, diff lock as you did, and then select 2nd or maybe even 3rd gear. Set off gently and increase speed steadily.  This way you can use momentum to help with progress if you happen across a sticky bit.  1st gear is too low, hardly any momentum; you are totally relying on the grip of the tyres at any point in time with no momentum to carry you through.

Hope that makes sense.

I believe the mud tread pattern you have is ideal for the conditions we mostly see in Britain and certainly better than a road tyre in snow.  A dedicated winter tyre would obviously be better on snow, but would be useless in mud...which I imagine you encounter much more of !
Title: Re: Driving a 4x4 in snow
Post by: Womble on March 15, 2018, 11:04:23 pm
Thanks Stufe, it's good to know at least one thing on my Landy still works then!!  ;D
Title: Re: Driving a 4x4 in snow
Post by: landroverroy on March 16, 2018, 06:49:34 pm
I too drive a defender, and find that 1st gear in high is similar to 2nd gear in low. (Not exactly  the same - before you all rush to correct me - but similar.)
There is therefore no point in going into low ratio for setting off in icy conditions. You are more likely, as Mab says to spin the wheels and lose what little chance of grip you may have had. So you may as well stay in high  ratio and set off with minimum revs in first. This way you can stay in first gear longer and build up more momentum with less chance of wheel spin before you have to change up.
I do a lot of off roading and driving through mud because of the rough land we graze,and have found the greatest improvement in grip on both rough land and ice was caused by changing my road tyres to more rugged ones. I don't mean ultra knobbly - just more off road type ones. The improvement in grip in adverse conditions is phenomenal.
 
Title: Re: Driving a 4x4 in snow
Post by: Glencairn on March 16, 2018, 07:40:33 pm
I wouldn't put my faith in tyres having the M+S marking, highway terrain summer tyres have it and that is clearly very different conditions to driving through a muddy snowed on field in a Scottish winter.

My last set were A/T and they were quoted as being 60% on road 40% off road tyres.

If I was spending a fair amount of time driving through fields I would buy mud terrains and put up with the extra road noise.
Title: Re: Driving a 4x4 in snow
Post by: Maysie on March 17, 2018, 11:27:14 am
I wouldn't put my faith in tyres having the M+S marking, highway terrain summer tyres have it and that is clearly very different conditions to driving through a muddy snowed on field in a Scottish winter.
I completely agree. 

My Hilux tyres are M&S rated, but they are pretty well useless on anything other than dry tarmac and totally useless in mud.  We have struggled through this winter with them, but I am hoping they have worn out by next autumn so we can replace them with more appropriate tyres for our general use. 
Title: Re: Driving a 4x4 in snow
Post by: Glencairn on March 17, 2018, 04:24:53 pm
I've driven Bridgestone Dueller highway terrain and they weren't great. A good all terrain tyre will do a lot better for the user that doesn't just want to drive on tarmac.

I put winter tyres on the car, simply because its relatively affordable to have a second set of wheels I'd really like to do the same on my jeep but need to find a second set of wheels at a scrap yard or online.
Title: Re: Driving a 4x4 in snow
Post by: Rupert the bear on March 17, 2018, 05:32:56 pm
My choice of tyre  :D
Title: Re: Driving a 4x4 in snow
Post by: stufe35 on March 17, 2018, 06:17:45 pm
The BF Goodrich Trac Edge tyre used to be the best balance of a tyre with nice road manners but performed well in mud / snow also.  It has decent lugs on the side wall which is the bit does the work in mud and a fairly continuous pattern in the middle givingg good road contact, but open enough for snow also.  It was commonly used on Range Rovers because of its excellent qualities.  Sadly BF stopped making it, but Insa now market the same tread pattern as the insa turbo traction. See it in the link below.  If you don't want out and out mud pattern designed for serious off roading but noisy on road the I would recommend these very strongly.  You will not find yourself embarrassed when driving across a wet field ideal for landrover.
The tyre marketed by BF as "all terrains" .and often copied are absolutely useless in mud, having no side lugs. The tread just fills with mud and you go nowhere. You might as well buy road tyres as them.

https://www.ebay.co.uk/itm/INSA-TURBO-TRACTION-TRACK-4X4-TYRES-235-70-16-FITTED-AND-BALANCED-PRICE/191377184519hash=item2c8ef81707:g:UfoAAOxynapRf8ft (https://www.ebay.co.uk/itm/INSA-TURBO-TRACTION-TRACK-4X4-TYRES-235-70-16-FITTED-AND-BALANCED-PRICE/191377184519?hash=item2c8ef81707:g:UfoAAOxynapRf8ft)
Title: Re: Driving a 4x4 in snow
Post by: pgkevet on March 18, 2018, 06:22:02 am
ultimate solution..

https://www.youtube.com/watch?v=XwpKjEa4LYY (https://www.youtube.com/watch?v=XwpKjEa4LYY)