[scubazealous]

They look like they would improve traction while moving, but when braking I could see the chains slipping out from under the tires letting the vehicle slide. Not fun on icy roads.

Seems like a great solution for light snow/mild ice but I would not want to trust my life to these in harsh conditions.

[dsfyu404ed]

A school-bus or box truck that will basically get stuck everywhere if it doesn't have something under the driven axle. Braking is not what's limiting the conditions these vehicles can work in. Getting stuck because you stopped at a red light on a slight hill is more their problem which is what these chains solve.

[just_boost_it]

Giving drivers a sense of control that doesn't match up with how the vehicle performs in braking looks like a pretty big design flaw to me.

[flandish]

These have been around for decades. Additionally, a lot of “braking” with these bigger trucks is “engine braking” like jake brakes, compression release, exhaust release, etc.

Can slow a lot by “simply” letting the jake engage.

We use them on our fire trucks, engines, tankers, etc, here in New England. Some of these apparatus way upwards of 30ton.

[Shivatron]

A two-wheel drive vehicle with an open differential is limited in acceleration by only one wheel (the drive wheel with the least traction). However, braking is always the combined effect of all wheels.

[mannykannot]

That's a fair question, though I would guess that, unless the wheel is locked, it is no more likely to slip out under braking traction than driving traction. That figure may well be higher than for fitted chains or studded tires.

AWD has the characteristic of improving driving traction while doing very little for braking or steering, as demonstrated by the guy who passed us and then rear-ended the mail delivery van.

[KennyBlanken]

In a true full-time AWD system when applying any power, there's half the torque which means there's more capacity for the tire to handle side loads from cornering/turning.

However, AWD in vehicles without traction control recovery from a slide is more difficult due to there being two different thrust vectors.

[mannykannot]

I take your point. I was thinking only of steering without drive traction.