Driving in the snow and ice - what do you do?

[Roxy4x4]

Originally Posted by cruising7388

Why are dual wheels detrimental in ice and snow conditions?

Sorry didn’t see this till now. The other gents have explained it very well. Your experiences may differ but personally if I had to choose between single rear wheels versus duallys for traction, single rear wheels wins hands down every time...

[cruising7388]

Originally Posted by booster

Absolutely horrible.

You can get some advantage by getting a van with a locking differential, but you need to be sure it is one that is not a full time limited slip (suregrip, positraction, etc) or a full time locker. We put a an updated rear axle into our Chevy and got one with a Gov-lock which only locks the rear wheels together if one tire is going considerably faster than the other. It also unlocks and won't lock at about 20mph so you don't get into the rear wheel drive locked rear end fishtail suicide run if you hit ice at speed. It is not going to help you turn, steer, or brake, but it will let you keep going in worse conditions without getting stuck.

I get this but it doesn't address why duals perform worse than singles in ice/snow/mud.

[cruising7388]

Originally Posted by Bruceper

The answer is thinner tires penetrate snow better and provide more weight over the smaller footprint.

The wider tire however does better in slush due to the displacement of the slush.

With modern winter tires the thin vs wide debate is pretty moot. They include a softer material compound with tread designed to shed the snow.

I'm still unclear why four rear tires are inferior to two rear tires when dealing with snow, ice, slush or mud or some perverse combination of all four.

[booster]

Originally Posted by cruising7388

I'm still unclear why four rear tires are inferior to two rear tires when dealing with snow, ice, slush or mud or some perverse combination of all four.

It appears to be the same reason big wide tires are bad, they tend to float on the surface of the snow rather than sink through it and compress it into the tread. They also have to move through more snow because of the width of the contact area. Tall skinny tires have a contact patch that is longer than it is wide, while wide tires (and duals) have a wider, shorter contact patch that isn't as good at packing the snow into the tread for grip. This is the explanation I have always heard.

[Davydd]

Michelin Defenders and a 3500 dually Sprinter works just fine in snow. We just got back from Tahquamenon Falls State Park in Michigan's Upper Peninsula. This is the worst we will attempt. The DNR plowed out the campsites but the roads still had packed snow. The UP is fairly flat. The main roads were mostly dry but last year we drove mostly on packed snow to get there.

[Bruceper]

One thing I will say, much of the tire "advice" I see on websites is the same information that was given in the mid eighties. In the mid eighties if you wanted winter tire performance you got a pair of studded bias ply tires and went nuts.

Tire tech started growing up in the late eighties and early nineties and has exploded since then. I remember in 1992 I bought a pair of winter radials for my then new 91 dodge D50. The things I could do were amazing! I could start and stop on ice like it was dry pavement. And since then winter tires have gotten better.

So (mostly) forget about dual vs single for winter, and think about all season vs winter tire.

[mojoman]

Here in the people's republic of California, we have had to learn how to drive in heavy snowflake conditions year round. Our horns have been replaced with squeaky toys.

[saenzm]

Originally Posted by Bruceper

One thing I will say, much of the tire "advice" I see on websites is the same information that was given in the mid eighties. In the mid eighties if you wanted winter tire performance you got a pair of studded bias ply tires and went nuts.

So sounds like all I need are a pair of winter tires when chasing snow and I should be good to go!

[booster]

Originally Posted by saenzm

So sounds like all I need are a pair of winter tires when chasing snow and I should be good to go!

Winter tires should always be used in sets of 4, form all I have ever heard, as you need to keep the front to rear traction balance, especially on dry roads.

[Bruceper]

Originally Posted by booster

Winter tires should always be used in sets of 4, form all I have ever heard, as you need to keep the front to rear traction balance, especially on dry roads.

Correct. Back in the day tire shops would say just the two back tires is fine, or the two front if you had front wheel drive. Move up to more recent times and they realize that you need all four corners for stability, stop, go and turning.

As I said, tire technology has changed a lot.

[Marley]

The problem with dual tires and traction comes down to PSI (tire contact). Dually pick up trucks w/o weight in the back just won't get traction anywhere...add a couple of thousand pounds over the rear axles and off you go.

Another trouble with dually trucks - at least the drywall delivery one I drove when I was 19 back in the late 1970's, is that in certain mud the area between the tires gets plugged up so you lose the bite of the inside lugs. Of course we were always driving on construction sites and had to learn many tricks to make a very hard physical job a little easier - not getting stuck was one...

[booster]

The psi thing about big or dual tires is interesting, for sure.

If you ignore the variations due to sidewall stiffness (or more sidewalls in duals) which is generally pretty small an amount of weight carrying capacity, single and dual tire will have the same amount of tire contact to the road, and will exert the same psi pressure on the road if at the same tire pressure. All that is determined by the weight on the axle and tire pressure.

The big thing that does change is the shape of the tire contact point with the road. Single will have a long narrow patch in the moving direction, and duals will have a long horizontal patch, which really affects how the snow is packed into the tread and lugs (if there are lugs).

Adding weight will increase the friction available, for sure, but what it also does is make the tire patch longer in the moving direction, also improving traction in snow.

What is even more interesting is that on dry pavement, pretty much the same thing happens, until the tires start to spin or slide, then it goes to exactly the opposite effect. As soon as you get to the point of sliding or spinning, wide tires work better than narrow one. Presumably, this is because of the fact that only the very front edge of the tire is seeing rubber to pavement friction, and all the contact area behind that is running on melted rubber, marbles of rubber, and some pavement, so there is less friction behind the front edge, making a long skinny contact shape less effective. Skinnies are dandy for long smoky burnouts, and burnout contests, however!! This is also the premise for antilock brakes, which show that rolling tires stop faster than sliding tires on dry pavement as they are getting full friction over the entire contact patch.

[Marley]

Tire pressure is a big factor as you say. We drop air pressure in our dirt bikes in the spring and fall because of the frozen ground - lot more contact area.

Same thing getting stuck in an RV on Pismo Beach in the sand - drop the air pressure to the point that the tires almost look flat and slowly crawl out of it.

[booster]

Originally Posted by Marley

Tire pressure is a big factor as you say. We drop air pressure in our dirt bikes in the spring and fall because of the frozen ground - lot more contact area.

Same thing getting stuck in an RV on Pismo Beach in the sand - drop the air pressure to the point that the tires almost look flat and slowly crawl out of it.

Yep, rough surfaces are one of the things that can actually defy the "normal" laws of physics, when combined with a soft surface like a very soft tire, which is was happens in lowering pressure in low traction situations on anything somewhat rough. Physics says friction is only dependent on total weight and coefficient of friction and area of contact doesn't matter, so what you describe shouldn't happen, but it does. In the case of things like this you actually get some interlocking of the surfaces, so it is not pure friction, just like the lugs on snow and offroad tires dig in and grab, basically tearing one of the surfaces. Of course, as soon as you spin the tires, you can tear off any grip you have, or dig a hole if it is soft, and it is game over.

Just the opposite can happen if both surfaces are hard, but have something that rolls in between them, like thin sand on pavement.