Those parameters aren't in GDB file, they are in TDF file and nor all of themWith this code in the GDB file we can adjust the grip and irregularity of the tarmac. Above all, the rumbles seemed a little dangerous to me, now it's a little better.
RoadDryGrip = 1.03
AIDryGrip = 1.03
RoadWetGrip = 0.88
AIWetGrip = 0.88
PlayerTireWear = 1.0
FrontTireHeatMult = 1.00
RearTireHeatMult = 1.00
RoadmetalGrip=0.80
RoadDustGrip=0.90
RoadBumpAmp=0.010
RoadBumpLen=13.0
RumbleDryGrip=1.05
RumbleWetGrip=0.80
RumbleBumpAmp=0.015
RumbleBumpLen=8.0
MiscBumpAmp=0.08
MiscBumpLen=4.0