What should I clean not very dirty tires with before dressing?

[Silverstone]

I wash the car often so it's never that dirty but if I'm going to re-apply a tire dressing do I need to scrub them, and if so with what? Can I just run a rag full of car soap over them during the wash and then apply more dressing?
How do you guys do it?

[IOMCAMARO]

I use an APC (Optimum Power Clean) and a tire brush that I bought at Wally World. It works like a champ.

[ScottB]

Aro ...

[BobbyG]

ARO = Amazing Roll Off
Wesley's Tire Cleaner
Meguiar's Super Degreaser
Optimum Power Clean

[Jimmie]

ARO here too.

[IID]

I used OPC in this thread:
http://www.autogeekonline.net/forum/product-reviews/39232-impressive-4-way-wheel-cleaner-test-tire-shine-comparison.html

:props: