Below is the selection menu for OptiTruck Weight Distribution. Choose a configuration and continue onto the input screen.

OptiTruck’s weight distribution modules provide a means for estimating axle loads, and provides a convenient tool for maximizing payload on a given truck or truck and trailer combination. OptiTruck has three basic weight distribution modules:

1. Straight truck – This module is used for straight trucks with a variety of axle combinations – single or tandem drive axles with as many as three lift axles in either case. OptiTruck allows the user to specify all of the parameters that define a straight truck in a well organized input form, or piece by piece using an input wizard that provides guidance on making appropriate data entries.
2. Straight truck with trailer – This module has the same components as the straight truck module, except that the user may consider a full or “pup” trailer as a means to increase payload. The user must specify the payload that is to be carried on the trailer, and OptiTruck will optimize the remaining payload on the truck bed. This module also has a wizard that will walk the user step by step through the entry process.
3. Tractor with semitrailer – This module allows the user to specify a conventional tractor and semitrailer combination and calculate axle loads and maximum payload.

In all three modules, OptiTruck contains enough warnings and stops to ensure that the data entered is reasonable. In addition, through the use of the input wizards OptiTruck gives expert guidance in entering values that make sense. In almost any weight distribution calculation, you will be guessing at something – often the best chassis curb weights you have are good guesses, body weights are rarely known with precision and things like fuel and driver weights are not only uncertain, but can vary over time. OptiTruck helps you make good and reasonable guesses where the values required for the calculation are not known with precision. OptiTruck cannot prevent every possible combination of bad input data, but it will flag or prevent most of the common ones.

Some configurations that are not suitable for calculation with OptiTruck include:

· Straight trucks with more than three lift axles
· Pup or full trailers with more than two axles
· Trucks or tractors with dual steer axles
· Tractors or semitrailers with anything besides a conventional tandem-tandem arrangement

The basic methodology by which OptiTruck calculates maximum allowable payloads is analytically intensive – i.e. it requires many calculations – but conceptually simple. For a given truck or combination, OptiTruck calculates the payload that maximizes the front axle load to its prescribed maximum, then calculates the payload that maximizes the rear axle load, then the payload that maximizes inner bridge law, then the payload that maximizes outer bridge law, and so on, through all of the capacity criteria that are applicable to a given combination. OptiTruck then chooses the least of those calculated payloads to report as the maximum payload. The chosen maximum payload will maximize one of the criteria that determines payload limits. The other axle loads are then recalculated based on that payload. While straight-forward for OptiTruck, these would be time-consuming calculations if you attempted them by hand, particularly given the iterative nature of the sales process for most trucks!