....I never considered using a complex toll app for Mexico (or, covering the US) as our rigs are SUV and 2500HD (pick-up) carrying truck camper. No dually, no towing.
I did more digging, and came up with an app that calculates:
-Auto: select from 2-axle cars, SUV, Carpool, Pickup with four tires, 6-tires, and 1-axle trailer attached.
-Truck: select from 2-axle trucks to 9-axle trucks. Enter the height and loaded weight of your truck.
-Bus: Choose between 2-axles or 3-axles. Enter height and loaded weight of the bus.
-RV or motorhome: Select whether you have a 1-axle trailer. Enter height and loaded weight.
-Motorcycle: Select whether you have a 1-axle trailer.
I never used it. It is called TollGuru. You can play with the interface, and enter exotic RV combos like motorcycle towing mini trailer; RV hauling double-axle trailer, etc, etc
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