Tire parameters

Example carparts/tire/touring

restitution = 0.1
tread = 0.25
rolling-resistance = 1.3e-2, 6.5e-6
# Lateral force
a0=1.55
a1=-55
a2=1750
a3=1900
a4=7.2
a5=0.014
a6=-0.24
a7=1.0
a8=-0.03
a9=-0.0013
a10=-0.15
a111=-8.5
a112=-0.29
a12=17.8
a13=-2.4
# Longitudinal force
b0=1.65
b1=-110
b2=1800
b3=23.3
b4=410
b5=0.075
b6=0
b7=0.055
b8=-0.024
b9=0.014
b10=0.26
# Aligning moment
c0=2.2
c1=-4.3
c2=-4.4
c3=-1.9
c4=-9.6
c5=0.0225
c6=0
c7=0.044
c8=-0.58
c9=0.18
c10=0.043
c11=0.048
c12=-0.0035
c13=-0.18
c14=0.14
c15=-1.029
c16=0.27
c17=-1.1

Restitution defines tire restitution(not implemented atm). The tread parameter ranges over arbitrary values of 0.0 to 1.0, where 0.0 is a road tire and 1.0 is an off-road tire. The two elements of rolling-resistance are the constant and velocity-squared terms, respectively. The longitudinal, transverse, and aligning section each contain a vector of “magic formula” coefficients as presented in Motor Vehicle Dynamics, Genta (1997). A description is shown below:

Shape factor ........................................... A0
Load infl. on lat. friction coeff (*1000)... (1/kN) .... A1
Lateral friction coefficient at load = 0 (*1000) ....... A2
Maximum stiffness ........................ (N/deg) ..... A3
Load at maximum stiffness ................ (kN) ........ A4
Camber infiuence on stiffness ............ (%/deg/100) . A5
Curvature change with load ............................. A6
Curvature at load = 0 .................................. A7
Horizontal shift because of camber ........(deg/deg).... A8
Load influence on horizontal shift ........(deg/kN)..... A9
Horizontal shift at load = 0 ..............(deg)........ A10
Camber influence on vertical shift ........(N/deg/kN)... A111
Camber influence on vertical shift ........(N/deg/kN**2) A112
Load influence on vertical shift ..........(N/kN)....... A12
Vertical shift at load = 0 ................(N).......... A13

Shape factor ........................................... B0
Load infl. on long. friction coeff (*1000)... (1/kN) ... B1
Longitudinal friction coefficient at load = 0 (*1000)... B2
Curvature factor of stiffness ............ (N/%/kN**2) . B3
Change of stiffness with load at load = 0 (N/%/kN) ..... B4
Change of progressivity of stiffness/load (1/kN) ....... B5
Curvature change with load ............................. B6
Curvature change with load ............................. B7
Curvature at load = 0 .................................. B8
Load influence on horizontal shift ....... (%/kN) ...... B9
Horizontal shift at load = 0 ............. (%) ......... B10
Load influence on vertical shift ......... (N/kN) ...... B11
Vertical shift at load = 0 ............... (N) ......... B12

Shape factor ........................................... C0
Load influence of peak value ............ (Nm/kN**2) ... C1
Load influence of peak value ............ (Nm/kN) ...... C2
Curvature factor of stiffness ........... (Nm/deg/kN**2) C3
Change of stiffness with load at load = 0 (Nm/deg/kN) .. C4
Change of progressivity of stiffness/load (1/kN) ....... C5
Camber influence on stiffness ........... (%/deg/100) .. C6
Curvature change with load ............................. C7
Curvature change with load ............................. C8
Curvature at load = 0 .................................. C9
Camber influence of stiffness .......................... C10
Camber influence on horizontal shift......(deg/deg)..... C11
Load influence on horizontal shift........(deg/kN)...... C12
Horizontal shift at load = 0..............(deg)......... C13
Camber influence on vertical shift........(Nm/deg/kN**2) C14
Camber influence on vertical shift........(Nm/deg/kN)... C15
Load influence on vertical shift..........(Nm/kN)....... C16
Vertical shift at load = 0................(Nm).......... C17

More information can be found at http://members.xoom.virgilio.it/adiaforo/epcjk.htm or if it's down try http://web.archive.org/web/20050913052226/http://members.xoom.virgilio.it/adiaforo/epcjk.htm

There is a graphical tire parameters editor to adjust/review the parameters: http://svn.vdrift.net/viewvc.cgi