I use HS Purple blaster , I only scrub when the tyre is extremely dirty or if extremely dirty i just spray it using pressure washer , as for hub caps its very strong I try not for it to dry or else it stains then wash the hub caps and tyres with diluted dishwashing soap
I have used Simple Green with scrubbing. Also use it on the engine.
I use HS Purple blaster , I only scrub when the tyre is extremely dirty or if extremely dirty i just spray it using pressure washer , as for hub caps its very strong I try not for it to dry or else it stains then wash the hub caps and tyres with diluted dishwashing soap