Regulated by tire or by axle? In the US, it’s generally the latter.
Re:Nickel Hydrogen Batteries by NASA
by marcosdumay on Wednesday September 27, 2023 @05:18PM
(#37681457)
Yes, by writing it by axle on the regulation is common. There is also a requirement for a minimum number of operating tires in an axle. (I don't keep close track of this, but I don't think it's always 2.) And requirements for tire pressure (that changes how much damage the truck causes too).
On practice the impact of the truck is determined by law independently of the weight (on those superficial models, but there is also some depth where the regulation starts to fail).
Divided by tire. That's why heavy trucks have so many of them.
Most countries regulate the weight by tire, so that this actually doesn't change between trucks.