This "solid paper" you’re likely after isn't just one document but a collection of industrial and academic research used to build the sim's realistic tire and bike behavior:
If you are looking for an academic foundation for (TDR), the developers have explicitly stated that the game's physics are based on the work of Vittorio Cossalter , specifically his seminal book Motorcycle Dynamics . trackdayr.rar
If you are specifically looking for a .rar file of these papers, be aware that many of these are copyrighted academic texts or proprietary industrial data. You can find high-level summaries and purchase options for Cossalter's work on major academic publishing sites. Are you trying to for a specific bike, or TrackDayR – The Unleashed Sim This "solid paper" you’re likely after isn't just
: The game integrates various validated industrial formulas to replicate accurate motorcycle movements rather than using simplified "arcade" physics. Are you trying to for a specific bike,
: TDR uses the Pacejka "Magic Formula" as the foundation for its tire physical model, which is the industry standard for simulating tire-road interaction forces.
: The developers highlight this as a primary source for their physics model.