don't pay the ransom, i've escaped. this looks like a fun discussion to stick my nose into. first multi-color road wheels. i don't do them. when driving they create a kaleidoscope effect and attract the eye. i do have my own tell, especially with warwheels. instead of painting all 8 tire hubs the base color i will take the camo color and, if the pattern would flow into the hub, paint it the other color. unless i'm doing a specific vehicle with photos. our M60A2s were brand new when we got them in '75 and that's how the road wheels were. and even though they were airbrushed the camo still had a sharp edge. but sharp vs soft edge on armor camo isn't a "fall on my sword" issue
i do paint road wheel tires dark gray instead of black and wash black rubber tires with a dark gray so they look used.
while we are here the whole rusty track thing doesn't do it for me either UNLESS it's an inactive vehicle. our steel wear plates behind the aluminum roadwheels would rust in the motor pool as would the track end connectors. nice dark brown rust and bright rust. half a day in the field and they are steel color shiny and dull, all the rust gone. someone here mentioned taking M-113s out for national guard training and 2 weeks later the entire belly plate was shiny aluminum from the paint wearing off.
some folks just paint everything below the fenders dirt/mud color and leave it.
now i do get artsy on some builds. i will make wood handles on tools wood instead of base coat painted just to add some color. i will wash with various oils to emphasis hatches, etc. i don't do a lot of chipping for the reasons for the same reason Bish says. as for environmental dirt and grime we had a platoon come back from, i think, baumholder and, because of the red clay, they were almost pink. and the trees along the the main tank trail at grafenwehr are permanently stained from the dirt mist that is sprayed from vehicles.
all that being said, this doesn't hold true throughout the world. i am doing a libyan BM-21 and have a bunch of pictures and these things are beat all to hell, chipped, faded paint, hand scrawled arab numbers and letters. i will show the kit when finished with the photos for proof. OTOH i am doing a URAL-4320 6x6 in orange civilian colors and it will be near pristine, just some road grime.
i better quit or my verbosity will cause folks to swear at the kidnappers for allowing me to escape.