Use notepad to look in the tdf file for the track.
Sometimes it is possible to reduce some of the bump magnitudes and make the road surface feel smoother. Make a backup first though in case you make it feel worse, but it is well worth a go.
Look for lines like :
RoadDryGrip=1.00
RoadWetGrip=0.80
RoadmetalGrip=0.80
RoadDustGrip=0.90
RoadBumpAmp=0.007
RoadBumpLen=9.0
RumbleDryGrip=0.95
RumbleWetGrip=0.60
RumbleBumpAmp=0.010
RumbleBumpLen=8.0
MiscBumpAmp=0.08
MiscBumpLen=4.0
Lower down, you will find
BumpAmp=0.012 BumpWavelen=3.0
and many others. Just work your way through, reducing the bump size and/or length.
**Beware you will probably have an online mismatch so this is for offline only**
This has worked well for me on some tracks.