AxleSet
Axle weight & tandem slide calculator for truckers
From where your tandems are right now. "3 holes forward" means three holes toward the cab from the hole they are in today. "Back" is away from the cab. The fifth wheel works the same way: "forward" is toward the front of the tractor.
Because it depends on your trailer. Weight moved per hole equals the trailer-axle weight times the hole spacing, divided by the kingpin-to-tandem distance. A 53-foot van at 40 feet with 6-inch holes moves about 420 lb a hole; with 4-inch holes, about 280. AxleSet calculates it for the trailer in your rig profile. That is why the profile matters.
In My rig, tap Calibrate from two weighings. Weigh, slide the tandems a known number of holes, weigh again, and type both trailer-axle readings. AxleSet works out the distance from the two numbers.
AxleSet tried every hole and every fifth-wheel notch you told it you have, and none of them gets every axle group under its limit. The card shows the closest it could get and what is still over. That is the moment to rework the load or drop weight — not to reweigh.
AxleSet only shows a state's limits when they were read on the state's own statute or DOT publication (or an archived copy of that official page). A few states block automated reading of their code, so their numbers are not shown until a person confirms them. For those states the app uses the federal Interstate limits and says so.
The lower number, and it tells you. For example, one federal example and one state table round the same bridge-formula case 500 lb apart; AxleSet shows the lower figure and flags the tie.
No. Never. Everything is on the phone.
No. AxleSet is a reference and a calculator. Laws change, permits change things, and the officer's table wins at the roadside. When in doubt, check with the state.