Tire model - missing value

Hello! We are a Student Formula team and are trying to model our own Tire to Carmaker. We’ve followed the FCM Tutorial and generated the .tir file from OptimumTire, but when importing, it says the following:


Firstly, did we do something wrong on OptimumTire? And what do these variables mean in a Tire model?
Thank you!

Hi Ricardo,

Welcome to the Forum! :slight_smile:

You can find the information about the MF equations and the meaning of the parameters in the Reference Manual under the section Tire - Tire Model “Magic Formula” (17.5)
QSY3 & QSY4 are Rolling Resistance Torque parameters depending on speed. So your file is missind this dependency.

You can open the Reference Manual: Main GUI → Help → Reference Manual

Best Regards

Thank you, Jose!

I didn’t read the Reference Manual, now it’s very clear to me. But, unfortunately, I’ve got other problems. We followed the OptimumTire tutorial to import TTC raw data and export it to a .tir file, so that I could upload it to Carmaker and generate a new Tire file.

As far as we are concerned, we checked every coordinate systems - just as FCM Tutorial has claimed. But when simulating our model, some problems emmerged:

  • ADAMS property file format was previously MF52; I’ve changed it manually to MF_05 so it could work;
  • Some values had opposite signals (positive x negative) when comparing with IPG examples of a Tire file. On an initial analysis, it seems like all of the inverted values has something to do with vertical load (Fz). For example, Nominal Wheel Load (FNOMIN) was negative when it shouldn’t.

Have you ever met a problem like this one before? Or do you have any guesses of what could it be? Thanks for your attention.

Hi Ricardo!

It looks like you have a problem with your reference system. You should check the tyre axis system in CarMaker and compare with the one that you are using in OptimumT to create your tir file. You can find the description of the tyre reference system in the section of Tire - Overview in Reference Manual.
As an extra note and in the same document have a look to

  • Additional parameter “Side” as it is used for asymmetrical tyres to internally mirroring according to the side.
  • Model.FITTYP = 6 if you are using MF5.2 (More information under Tire Model “Magic Formula” - Tire Description)