when do you shift from 2-wheel to 4-wheel drive?

Answer 1

Well when it snows or just plain crappy out put in in 4 wheel. Depending on what year and make of truck you have depends on whether or not you have to be stopped to engage four wheel drive

Answer 2

Well, the obvious answer is during times when there is snow, or slippery paths such as mud. But, as you get to know your vehicle, it'll become obvious that you might want to shift into 4-wheel drive when you know that conditions are changing....for instance, on a gravel road which goes from level to a significant grade upwards which might cause rear-wheel only drive to slip badly. See the below link for further good information.

Answer 3

Whenever your common sense warns you that it would be better to go four wheel drive, do it.
Some vehicles you have to get out and physically engage the hubs, do it at a safe place , rather than wait till you get to bad spots.
It is good practice to first get out and check the terrain where you are going to drive.
When the road is slippery , soft, icy, in snow , more than normal incline or decline it is safer to have four wheel traction.
Don't forget to disengage when conditions are good again, unnescessary tyre wear, more fuel and more moving parts.
In soft sand it is advisable to let out some air till the tyres have the baloon effect.
Good to carry an electric air pump that works off the battery or lighter socket.

Answer 4

Not being a smart-A-- , but if you don't know that, you should have someone show you, because I think you need the experience. Is this your first 4x4 ? Have someone teach you.
If you are not used to it, you need a `hands-on'. You'll catch on.

Answer 5

When you get stuck so you can back out.