Tires:
In Forza, weve always focused on our tire simulation. As a result, weve struck up multiple partnerships over the years to get tire data. In the past, weve worked with Goodyear, Toyo, and Michelin. We also used reference data from the Society of Automotive Engineers (SAE). In past Forza Motorsport games, we even featured tire carcass flex, tire surface heat, as well as tire gas heat and expansion. However, the model was based on a combination of data from all of our previous partnerships. And we had to do fix-up on the data to make all of the different data formatting play nicely together.
For Forza 4, we took an entirely new approach to our tire simulation. This time, we threw all of the old data away and asked Pirelli to provide us with all-new data for everything. Pirelli did custom tests on a huge variety of tires to cover all of our casesincluding tire width and height, compound, inflation pressure, heat, wear, sidewall height, load, angle, etc. We then changed our system to accept the real-world data directly and without any fix-up from us at all. This means that the tires in Forza 4 behave exactly as the Pirelli test tires did, even in complex situations where multiple parameters are changing rapidly.
Just looking at graphs of the Pirelli data versus our Forza 3 data, there are several obvious differences. Unfortunately, Im not permitted to expound on the data differences. As part of getting this level of access and partnership from Pirelli, we have to keep their data completely under wraps. From a gameplay perspective, these changes are most noticeable as you move load from tire to tire. There is a lot more nuance in the model than ever before.
