I'd talked to a few folks about tire cleaning at the meet and greet and wanted to share what I've just discovered as a pretty awesome tire cleaner.
I sprayed it on the truck and trailer prior to the M&G after 3 weeks of mountain and logging road mud had dried on them from hauling the camper in and out of a friends land. The dirt lifted out of them very quickly and a fast scrub and rinse left them looking great.
Follow the precautions cause it's pretty nasty stuff.
Also, word of caution with tire shines... if you spray/apply excessively and hit the road, they will 'grease' the side of your tow vehicle or trailer.