Normally tells you on the Ministry Plate
"18 wheeler" referred to tractor-trailer units with a total of five axles (four wheels per drive and trailer axle plus two wheels on the steer axle = 18 wheels). However, it has become a common expression for tractor-trailer units in general, whether or not they have 18 wheels.
18 wheeler has the higher gross weight
The same amount it could with tandem axles... you can put 40,000 lbs. on a 10' spread, but it doesn't increase the gross weight you're allowed.
Four to eight miles per gallon, depending on gross weight, powerplant, drivetrain, and terrain.
No. You'll have two slack adjusters per axle, assuming it's using s-cam foundation brakes all around - disc brakes don't have slack adjusters.
Could be as cheap as $2 (1 axle) to $25 (18 wheeler) or your life.
What's typically referred to as an 18 wheeler has five axles - steer axle, two drive axles, two trailer axles. Tractor-trailer combinations can have less or more,, depending on the application.
It doesn't matter what the trailer type is.. for an 18 wheeler engaged in interstate commerce, and without requiring an overweight permit, the allowed gross weight is 80,000 lbs.
Depends on the configuration. For a standard five axle setup, without requiring permits, a gross weight of 80,000 lbs. is permitted. The steer axle is typically permitted 12,000 lbs., but can actually be loaded up to 20,000 lbs., if the axle and tyres are rated for that sort of weight (most are not - you have to be running 425s or 435s on the steers to get that weight rating - most OTR trucks only run between 275 and 315s). The two drive axles are permitted a combined weight of 34,000 lbs. Tandem axles on the trailer are also permitted 34,000 lbs. between them, although 40,000 lbs. between the two axles is permitted if there is a spread of nine to ten feet between the axles (this is often seen on flatbeds).
Question How long does it take to stop a 18 wheeler with gross weight 80000 pounds at 65 mph on a good day and dry roads?
That depends on the weight, and whether you're simply over weight on a set of axles, or over your gross weight.