In line with your offer to ask you "anything", is it possible to know what proportion of a car's weight is lifted when you jack up on one side to change a wheel? Presumably some of the weight is being taken by the two wheels that remain on the ground. I ask this because, for a different job unrelated to the car, I want to buy a small hydraulic bottle jack (the smallest smallest possible to fit into a particular space) and I'm wondering if the max lift of the bottle jack is less than the total weight of the car, would it be safe to use it for changing a tyre.
As always, many thanks in advance, Philip
Filed under miscellaneous - Asked by Philip Donegan (Ballina) - Sun, 28 Oct 2018 08:58
In very simple terms, the jack must be able to take at least half the car's weight. Actually, to be safe, you'd have to say a little more than half, just in case there is any variance between passenger and driver side. Every car has its own weight distribution and centre of gravity, but for the purposes of this, imagine a car with its weight perfectly distributed. Position the jack in the middle of the side of the car and jack it up. When viewed from the front or back, the centre of gravity moves to the side of the car not being jacked up, so as the car goes up, the jack is actually under less strain than when it started.
With all of these things, we would recommend building in a safety factor, of course, and use a fixed stand to hold the car up before you go underneath it.