In general, full-size trucks are all about the same width and there are reasons for this.
The Tesla Cybertruck will not be some small, mid-size pickup truck. Rather, it will be a full-size electric pickup truck and, as such, certain size measurements are expected. Tesla CEO Elon Musk had initially said that the production Cybertruck would only be 80 inches wide. He now says it will be closer to 82 inches wide. Why the change in plans?
Go wide or go home
Most full-size pickup trucks are around 80 inches wide these days and with each new generation of truck, this figure seems to grow ever-so slightly. The width matters for several reasons.
The first and foremost reason why width matters is in relation to bed width. Truck beds are expected to have an internal width of at least 60 inches (but typically closer to 65 inches), but more importantly, there needs to be at least 48 inches between the wheel wells. This allows for 4-foot wide pieces of construction material to fit inside without having to rest on the wheel wells.
Ample width for 3-across seating
Trucks are expected to easily be able to seat 3 passengers across both the front (if properly equipped) and rear rows of seating. Furthermore, it's expected that these 3 passengers might all be adult-sized (think construction workers traveling to a jobsite). so a minimum width is expected for comfortable seating with 3 adults in either the front or rear or both.
When you're towing a wide load, the mirrors must extend out to a far enough point so that you can somewhat see around that load.
Most trucks offer specific towing mirrors that extend outward further than the standard mirror, but still, if the base truck was too narrow, then no amount of extended mirror would provide you with an adequate view and what's behind what is being towed.
Gallery: Tesla Cybertruck
So, while Musk may have wanted the Cybertruck to be a certain width, the reality is that truck width is more or less determined with the above requirements in mind. An 82-inch wide Cybertruck it is then.