Soft mud flaps are not a good idea for any 4x4.
If you ever go off-road and the terrain gets rough to the point where you want to back up - you will most likely lose your mud flaps (if they are soft). I have found hundreds of mud flaps over the years on rough terrain (mostly Toyota). The soft mud flap might get pinched between an obstacle and the tire when reversing and since the tire rotates now backwards it will rip the mud flap off the body.
A stiff mud flap resists getting pinched between tire and obstacle somewhat better (newer Toyotas have stiff mud flaps).
This is one of the many mud flaps I found laying in the dirt.
More basic off-road driving tips coming soon
Topics so far:
rocks on road I
rocks on road II
save your paint
rocker panel clearance
how to use automatics off-road
why to deflate tires for sand
who invented 4WD ?
most unique 4x4
future of 4WD?