Russian logistics are built around rail lines, as they are more efficient. Per Russian doctrine you are going to struggle to supply large numbers of forces beyond 50 miles from a railway line. You need to understand just how much stuff a modern army needs. Estimates from WW2 calculated that for every soldier in theatre they needed over 4 tons of material a month (that's ammo, food, medical supplies, replacement parts for vehicles and equipment, fuel, etc). And those numbers are likely higher in the modern era, with heavier and more powerful vehicles, increased usage of electronics, and munitions like missiles. A US armored division (on the order of 270 tanks and a similar number of other vehicles) on the move would consume 500,000 gallons of fuel per day.

Adding more trucks can even make the issues worse, since they need their own fuel, spare parts, maintanence staff, drivers, military police to provide security, etc. You basically have to use the rocket equation when accounting for logistics