Speaker cleaning and maintenance

Hello everyone, I been wondering if people here have a tried and true way to clean speaker drivers, I usually dust them with a soft brush and sometimes compressed air on the low setting, however, my rubber surrounds are getting a bit "discolored"  and I been wondering what additional cleaning technics people use... rubber treatments? disassemble? anything I am willing to check.
every easter i load my speakers in the bed of my pickup truck and run through a brushless car wash

make sure it is a brushless wash, you don't want swirls on the finish
Hot and dusty where I live.. Vacuum with a brush attachment. If I see surrounds getting too dry I’ll treat them. I only use Silicone or BR surrounds so silicone is the best treatment on the surround, not the binder (glue). I apply the silicone with a lent free rag. I have 50 year old BR surrounds and 75+ on cloth/wire surrounds. They will last another 75 years.. The suns UV are the killers..

I quit dong the car wash thing.. Every time I let them dry out... :-)

After running my speakers through the car wash, the sound was a little watered down.