Question on those truck tires that don't touch the ground?

Question

Can someone please explain to me why some heavy duty trucks, such as dump trucks or garbage trucks, have those tires that don't touch the ground? I don't understand the logic of them. I realize that the extra axels are for when the trucks are a carrying heavier loads then normal, but why are the tires just hang there in the air instead on the ground? Is it to save wear and tear on the tires?

Answer 1

pretty darn smart are ya.? also ,when the axle is being used it changes the way the truck will turn.

Answer 2

Good question and good self answer.

Answer 3

You are basically right that it is to save wear and tear on the tires. The extra axles are called pony axles and on most trucks are operated from inside the cab with an air valve. The reason you see them on  trucks is so that the truck can haul heavier loads, thus increasing the revenue of the truck. When the truck is fully loaded, those wheels must be on the ground to be legal, However almost every driver will raise them when making a turn to save wear on the tires from sliding them sideways thru a turn. If a DOT officer sees them do it, it is still illegal and they can write them a ticket for being over weight. And don't be fooled there are cops that are big enough A holes to write that ticket.

Answer 4

Yes you answered your own question.

Answer 5

I think you answered your own question

Answer 6

The tires that hang up in the air not touching the ground are not there to take weight off the other tires. On certain heavy haul dump truck/trailers, box trailers seen mostly in Michigan where they are legal, that wheel the extra wheel, is a weighing wheel. It is used mostly for weighing the load initially, where all the wheels on the ground surface helps even out the overall weight in the trailer, and then propped up. If that wheel was touching the ground, and the driver needed to go left or right, he/she would be going straight instead.

Answer 7

correct .. it is to save wear and tear on the tyres. The more axles on the ground the more load can be carried by the truck. When they get weighed to check the load each axle weight is weighed individually.

The suspension is controlled by air bags so when they are empty they can raise one axle off the road to save wear and tear on that axle and considering the cost of each tyre is $1,000 would be worth it in the long run

Answer 8

your right 50%. the other haft is the more wheels you have on the ground, the higher the fuel consumption. if you can save a gallon a day by raiseing the wheels off the ground, and the truck works 300 days a year thats $900 you lower your operating cost. get it?