Pacejka '96 examples

[KSP]

Hi people,
You are professionals here, but I'm just autosim gamer. Now I try to tweak physics of Racer free car simulator (www.racer.nl) in attempt to make driving a car more realistic. There are using Pacejka '96 tire model, but I can't find proper coefficients for achieve realistic behaviour of the tires. Can you show me some examples of proper coefficients for Pacejka '96? Mostly interested in 205/55 R16, 225/40 R18 stock tires and 225/40 R18 slick?

[mech5496]

I do not think that someone will give you tire data for free here; but I'm quite sure Avon has (or at least had) some tire data on their website, so you might want to check it. If I can recall, no Pacejka coefficients though....

[exFSAE]

Originally posted by KSP:
Hi people,
You are professionals here

No.

[JDS]

Originally posted by KSP:
Hi people,
You are professionals here, but I'm just autosim gamer. Now I try to tweak physics of Racer free car simulator (www.racer.nl) in attempt to make driving a car more realistic. There are using Pacejka '96 tire model, but I can't find proper coefficients for achieve realistic behaviour of the tires. Can you show me some examples of proper coefficients for Pacejka '96? Mostly interested in 205/55 R16, 225/40 R18 stock tires and 225/40 R18 slick?

It doesn't quite work like that. The Pacejka coefficients are the result of a tires characteristic found by testing the tire on a machine that measures forces.

If you are wanting the coefficients for an imaginary tire, you need to start by defining the characteristics of the tire, and then using the coefficients to match those characteristics. In other words, you need to determine how much lateral and longitudinal force the tire should generate at given loads, slip angles, and inclination angles. Then you need to plot the forces vs slip angle/ratio using the magic formula and adjust the coefficients to match the desired characteristics. This is EXTREMELY difficult to do though and will require a ton of trial and error and isn't really the proper way to do a tire model (it is reversed).

The way it generally works is a tire is tested, and the results are recorded. Then an algorithm of sorts is used to determine the coefficients to best fit the data.

So to answer your question, there aren't any proper coefficients for the tires you specified(although there certainly are improper ones).

[Zac]

For your purposes I'd recommend using a reduced order pacejka model like the one that is incorporated into Bosch LapSim. Actually, if you just borrow their tire model (Bill Cobb posted a version of it on the private TTC forum, I don't know if it is posted here), you can just use the coefficients from their software.

[mech5496]

If you want some "typical" coefficients (as typical as tire data can be) go to ->
http://www.avonmotorsport.com/...rce-centre/downloads (http://www.avonmotorsport.com/resource-centre/downloads)
select the tire you want and go to Pacejka model data (or something like that). This should give you an idea...

[BillCobb]

205/55 R16, 225/40 R18 stock tires and 225/40 R18 slick

You didn't mention the brand, pressure, usage, tread depth or rim width. Quite a difference between a Vibe/Matrix tire and CTS/V tires. Or were you thinking round and black makes the coefficients basically all the same (except for A0 and sometimes P56a of course).