mswscco

Part of the paperwork we had fill out at the dealer was a half-sheet that said tire chains can NOT be used with our 4runner. Any idea why? Thanks in advance.

Glenn

Did you ask the dealer?

rimpainter.com

Because if will screw up your diff if you run in 4WD with chains on.

mswscco

The sheet said to look at the owner's manual for clarification. The manual just says to make sure you have the right size chains before installing.

rimpainter.com

Yeah, see what the dealer's reasoning is on that one.

mswscco

How about running 4WD without locking the center differential? I was reading somewhere that VSC (which is disabled as soon as you lock the center dif) is preferred for level snow driving.

rimpainter.com

I dont know much about center-locked diffs...anybody else?

zedex

If your runner is anything like my Tacoma. There is very little room on the front for chains. I think the chain will grab the upper ball joint and cause all sorts of problems if not destroy the front end. Stick your head in the wheel well and have a gander.

mt_goat

Well I am trying to imagine a situation where you would need both 4wd and chains. If you are on a mountain pass that requires chains put them on the rear an leave it in 2WD. If you are in an "on-road" situtation where 2WD with chains is not enough then the Hwy Patrol will have closed the road or pass anyway.

If you are talking about an "off-road" adventure then my thoughts are if you are on a slippery surface then the different rate of rotation between the front and rear diff will be ok because the slip of the tires in the snow will relieve any stress on the center diff. Just be sure to shift back to 2WD if you hit a section of the trail where you have good traction.

And yes chains are for the rear only.

zedex

I was in that situation last week Mtn goat where rear chains would have done nothing for me. I was getting firewood and i slid off the trail down a slope in slick snow. I couldnt back up because i was against trees. I couldnt put chains on the back because they would have drove me deeper down the slope because my front tires completely lost traction. I needed chains on the front or a tow up the slope. I didnt have my winch in, which would have got me out in 2 minutes. I had to get pulled out by a dodge 4x4 duelly diesel who also got stuck. lol.
The good news. 2 years fire wood out of 1 huge fir tree and no dents.

rimpainter.com

I think Dale was referring to "normal" driving situations in the snow.

ewarnerusa

I drove with chains on the front this weekend, no prob. I was in some off-road snow conditions. I still got stuck (high-centered on snow), but after digging the snow out from underneath I backed out. Tires are stock size, no lifts.

As far as which tires to put only one pair of chains on in a 4WD, it seems like everyone has different opinions. I have settled on the front for off-road conditions, and I haven't considered needing them in an on-road condition. I like this breakdown from another thread (Thanks oly884).

"If you're going "off-road" as in off pavement put them in the front. A perfect example of this would be deep snow. You want to pull through deep snow, having them in the front accomplishes this. If you put them in the rear, you are going to be pushing your front tires into the snow.

On road, put them in the rear. More than likely the roads won't have more than a foot of snow on them. You also will be traveling at a higher speed. Since that's the case, if they were in the front and for whatever reason you had to stop quickly, your back end would want to keep moving forward and you would spin out. With them on the rear, it isn't impossible to do that, but it's much less likely."

Glenn

Leave it in 2wd? I wouldn't dram of it on a snow/ice covered pass. The front axle makes a huge difference, chains or not.

jruz

How would a snowmobile fit in this equation? In the front the skis just give you direction...and in the rear the treads dig in and push you forward.

I think in deep snow I would want to be pushed, not pulled...hoping that my front tires would "float" (relatively ) and give me direction. If they have chains, they might be inclined to dig me into the snow.

Example 2...desert runners. Most of the time they are just 2wd. They don't want the front wheels to dig in.

Anywho, that's my take on the physics of it.
Jim

oly884

Glad to be of assistance

oly884

Well, a snowmobile is much much lighter than our trucks or 4-Runners.

What I was trying to get at with the chains in the front was that, if your tires were covered a fair amount in snow, then the chains in the front would pull the tires up and forward. If you had the chains in the rear, and your tires were covered a fair amount in the snow, it would be hard for your vehicle to try and push the front tires up and forward. The reason i say this is because i had an expirance earlier this winter where this happened to me.

Keep in mind though that it will probably only make a difference if your tire is halfway covered with snow. Not too many people get into situations where they are traveling through over a foot of fresh snow.

Also, the desert runners. Yes, sand is somewhat like snow, but the front tires won't really sink in the sand like they would in deep snow.

mswscco

Thanks so much for everyone's input so far. I was really more curious than anything else.

In any case, I just got off the phone with a tech supervisor at the dealer who said I wasn't the first to call with that question and he has no idea why sales is having people sign that waiver. He recommended cables over chains, which got me thinking that maybe the waiver was specifically referring to chains while not excluding cables?

ewarnerusa

snowmobiles have skis and a track with quite a bit more surface area in contact with the snow than any four tires ever will, even these tires. So you can't really compare these types of physics. And if tires worked as well as skis, then we'd see more winter downhill biking and less downhill skiing! I think skis are based more on planing or hydroplaning along the top of snow, where as tires are meant to dig in.

You always hear about how skinny pizza-cutter tires are actually better in snow rather than wide muddin' tires. I don't know the physics behind that one, either. But that's what they say... Can someone explain it for us? It is a good point you have, though, about comparing snow conditions with desert sand. I would imagine they are similar, but I can't think of a single example of how 2wd is better than 4wd in snow.

zedex

In off road situations in snow or ice ,chains on the front work alot more effectively . All your weight is up front. In snow the front wheels pull you and the rear wheels follow behind in the tracks left by the front. If you were to put chains on the back, the front wheels would plow somewhat and steering would be difficult as the fronts wouldnt have the same traction as the backs. Whats better in snow? Front wheel drive or rear wheel drive? Front wheel drive hands down.

Robinhood150

Skis don't work the same way a tire does. skis cut into the surface of the snow with the hard, sharp edges. Since tires have no hard sharp edges and the edges that it does have are so small in comparison to a ski, they do nothing.

Tires give directional control by gripping the snow through what little friction there is, instead of sliding and cutting. This is why on ice, tires are almost useless...they can't grip.