Well....here it goes.
It seems I have stains on my tyres from brake dust that gets loosened when I wash the car.
I noticed originally that about an hour after washing, there would be an occasional dirty, rust residue on the bottom of the wheels (run off from the brakes )
I would usually just squirt some water on and wipe off. Unfortunately, it seems some of it has run on the tyre and now I have reddish brown stains on the tyres
Also washing the tyre doesn't help.
Thanks for any tips

 

Once the rust stains are in the rubber, you'll have to work at it to get them out. Try scrubbing them out with a very stiff short bristled brush and car wash soap. If this doesn't work well, then get some commercial spray can of tire foam and go at it with the brush again. In future, after you wash you car, you might consider getting a high speed leaf blower and give each wheel a blow dry so they don't drip. I do this as well as blowing all the crevices like the mirrors, door handles, fuel door, etc and the car doesn't have the chance to drip.