Target audience: Vehicle dynamists, Research scholars, FSAE/Baja students
Read time: 10 minutes
Author:  Aravind R Nair

The beginning of road interaction of any vehicle model will start from the complex representation of tire models and its read interaction. It is considered complex because of its non-linear behavior on longitudinal and lateral slips, but that would just be the start of its modelling comprehension only. The overall material and structural build of tires gives rise to a visco-elastic property, which creates an impending “hysteresis effect” which means the stiffness/damping properties of the tire will be different for loading and unloading cases. Effect of suspension geometry comes up as a factor as the orientation of tire angles and position can change during a run, which gives rise to asymmetry in the tire contact patch. On top of that, the tire temperature, pressure and coefficient of friction between road and tire varies for in given time depending on the loading condition. Finally, the tire’s adhesion, cohesion and wear properties can affect its performance by repetition of test cycle.

It would feel like an impossible task, but the industry preferable tackle it by using the different tire models developed for different vehicle model test applications. It depends on your vehicle model application, fidelity, and cost. In the end, every company must balance a relationship between the quality and cost of any given product, of which the goal is to find the highest return on investment. That being said, the tire model selection process uses this principle while factoring in the model’s intended application.

How are tires tested?

Tire testing is generally performed using several approaches:

Indoor Flat-Trac / Flat-Belt Testing

• Calspan is famous for its large flat-belt tire testing machines, which measure forces, moments, stiffness, and contact patch characteristics under controlled conditions.
• Other facilities and equipment suppliers also operate similar systems, such as MTS Flat-Trac machines and university or OEM tire laboratories.
  

Drum Testing

• Tires are tested against a rotating steel drum for endurance, high-speed, rolling resistance, and durability evaluations.
• This is commonly used by tire manufacturers because it is less expensive and more readily available than large flat-belt systems.

Vehicle-Based Proving Ground Testing

• Tires are mounted on a vehicle and tested on tracks and proving grounds.
• Data collection uses wheel force transducers, IMUs, GPS systems, and subjective driver evaluations.
• This is essential for capturing real-world effects that cannot be perfectly reproduced in a laboratory.

Road Testing

• Tires are evaluated on public roads under different weather, pavement, and wear conditions.
• Often used for validation after laboratory and proving-ground testing.

Virtual and Hybrid Methods

• CAE, finite element analysis (FEA), and multibody simulations are increasingly used alongside physical testing.
• Physical test data is still required for model correlation and validation.

For tire model development specifically (MF-Swift, CDTire, FTire), engineers typically use a combination of:

• Flat-belt force and moment data (often from Calspan or similar facilities),
• Cleat and ride tests,
• Durability and road-load measurements,
• Vehicle-level validation data.

In practice, Calspan is considered one of the gold standards for generating high-quality force and moment datasets for tire model parameterization, but tire manufacturers such as Michelin, Bridgestone, Goodyear, Continental, Pirelli, and OEMs often have their own testing facilities and may supplement Calspan data with track and road testing before creating final MF-Swift, CDTire, or FTire models.

Prominent tire models used

Vehicle simulations play a critical role in improving handling performance, ride comfort, and safety, which are key customer-focused attributes and essential for meeting regulatory requirements. However, selecting the appropriate tire model and testing facility is not always straightforward. The optimal choice depends on several factors, including the intended vehicle application, required model fidelity, available test data, and overall project budget. As with any engineering decision, organizations must balance performance, accuracy, and cost to maximize return on investment. Consequently, tire model selection is driven by the specific objectives of the simulation study and the level of detail required. Widely used commercial tire models include MF-Tyre, MF-Swift, PAC2002, FTire, and CDTire, each offering different levels of fidelity and computational efficiency. These models have become industry standards and are extensively utilized across vehicle dynamics, ride, handling, durability, and safety development programs.

Siemens MF-Swift/MF-Tyre

Developer: Siemens / TNO
Best for: Steady-state handling, vehicle dynamics, tire force prediction

• Based on Pacejka’s Magic Formula and essentially a semi-empirical tire model.
• Accurately predicts tire longitudinal, lateral, and aligning force characteristics.
• Requires force and moment test data for parameter identification.
• MF-Tyre uses a single point contact tire model which oversimplifies the tire-road interaction
• MF-Tyre accurately simulates steady-state and transient behavior up to 10 Hz for handling, control prototyping, ADAS analyses and non-linear transients.
• MF-Swift extends MF-Tyre by incorporating transient behavior, short-wavelength road inputs, enveloping, and additional dynamic effects.
• The MF-Swift model calculates vertical and longitudinal tire modes up to 100 Hz and is primarily used to analyze ride comfort, road load, durability and vibration phenomena.
• MF-Tyre/MF-Swift supports usage for both desktop applications as well as on Real-Time systems.

Common users: Automotive OEMs, motorsport teams, tire manufacturers, and research institutions.

PAC2002 (Pacejka 2002)

Developer: Hans B. Pacejka / Delft University of Technology
Best for: Vehicle dynamics, handling analysis, control system development

• One of the most established versions of the Magic Formula tire model mostly in semi-empirical format.
• The biggest difference is that MF-Tyre is licensed by TNO, in conjunction with Siemens, and PAC2002 is licensed by MSC software.
• Extends standard steady-state equations with contact-mass or stretched-string models to simulate transient responses up to 8–12 Hz.
• Extended functionality that increases the validity towards short road obstacle wavelengths (with use of the 3D Enveloping Contact) and higher frequencies (up to 70 – 80 Hz) by using the tire belt dynamics modeling.
• Handles turn-slip, parking torque at zero speed, and camber angles up to 15 degrees.

Common users: Universities, research organizations, OEMs, and simulation software developers.

CDTire

Developer: Fraunhofer ITWM / MSC Software (Hexagon)
Best for: Ride comfort, durability, rough-road analysis, and full-vehicle simulation

• Physics-based flexible tire model capable of representing tire structural deformation.
• Special focus on tire belt dynamics and interaction with 3D road surfaces accurately captures the vibrations in both amplitude and frequency behavior with additional capabilities in static and stationary tire behavior
• Captures transient road-tire interactions more accurately than empirical tire models.
• CDTire needs geometric road surface models that return surface positions and a road-side friction coefficient.
• Accurate in frequency range up to 150 Hz
• Supports integration with multibody dynamics and finite element solvers.
• Complete 3D shell based model of sidewalls and belt, Hard real-time capable, Detailed thermo-dynamical model to predict temperature creation and propagation in a tire, and Can be used for modal analysis and imported into NVH tools

Common users: OEM durability teams, NVH engineers, ride and comfort development groups.

COSIN FTire™

Developer: COSIN Scientific Software
Best for: Ride comfort, NVH, durability, and road surface interaction studies

• High-fidelity structural tire model with detailed representation of tire flexibility.
• FTire is a physical tire model, meaning that the formulation of parameters is coupled, and directly correlated, with the physical structure of the tire
• Accurately captures tire response to complex road profiles and obstacles.
• Considered one of the most accurate tire models available for ride and durability simulations.
• The model separates the tire into numerous belt sections and captures the relationship between each section as it relates to the tire as a whole.
• Methods used by FTire enable short and large-waved obstacle measurements to model the tire’s modal response up to 200 hz.
• Requires detailed road and tire characterization data.

Common users: Premium automotive OEMs, research institutes, and advanced vehicle dynamics teams.

RMOD-K

Developer: Various commercial implementation providers
Best for: Vehicle dynamics, optimization studies, and efficient ride simulations

• Reduced-order tire model designed to balance accuracy and computational speed.
• Captures key tire flexibility and contact patch characteristics.
• Suitable for large-scale simulation programs where computational efficiency is important.
• Often used during concept development and design optimization activities.

Common users: Simulation engineers, CAE teams, and vehicle development organizations.

RMOD-T

Developer: Various commercial implementation providers
Best for: Full-vehicle dynamics, ride, and durability simulations

• Advanced reduced-order structural tire model with improved dynamic behavior representation.
• Provides greater fidelity than traditional empirical tire models while remaining computationally efficient.
• Well suited for vehicle-level simulation involving tire-road interaction.
• Supports both ride and handling development activities.

Common users: Automotive OEM CAE groups and simulation specialists.

FEA Tire Models

Developer: Abaqus, ANSYS, LS-DYNA, PAM-CRASH and other CAE platforms
Best for: Tire design, structural analysis, impact events, and material development

• Detailed finite element representation of tire geometry, materials, and construction.
• Used to study stress, strain, temperature, wear, and structural durability.
• Provides the highest level of physical fidelity among tire modeling approaches.
• Typically used during tire design and validation rather than routine vehicle simulations due to high computational cost.

Common users: Tire manufacturers, advanced R&D groups, and CAE specialists.

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