Pacejka and applying it

Heya guys,

I’m working on a semi-realistic arcade style racer. The WheelColliders just don’t do well for me, and I decided to create my own vehicle physics. I have create a suspension system that works really well, and I hope to go from here. (it took me about 4 weeks of coding, deleting and more coding to get it to work realistically, but having to sort through all the formulas used in real calculations such as Hooke’s Law have really helped.)

Now, I want to use a Pacejka model for my tires. It doesn’t really matter which version (87, 94 or 96, all okay with me). I know Pacejka is not an easy topic, but I hope to at least get some pointers in the right direction.

I have the Pacejka formula all worked out. The variables change based on my input, and the mass and gravity and stuff like that affect the script.

However, I’m stumped now on how to apply the Pacejka numbers to my actual wheels. I suppose I’ll have to use the hit.normal data from my suspension Raycasts, but even then, how to apply it and in what direction etc, just baffles me. Not to forget the combining of the longitudinal and lateral forces I have calculated. Unfortunately nowhere I found any info on that specific area.

So my question to you is, could you help me in the right direction? No need to post complete code sections, I like to learn (why I started this project in the first place), but pseudo code or just an explanation would be nice.

Once my car physics engine is finished, I’ll most likely release it for free.

Thanks for reading!

Kind Regards,


This reply is way late, but the old Unity car tutorial has an example of a Pacejka implementation. It’s in the AlternatePhysicsModel folder.