There's whitewall tire cleaners on the market, but they only do a fair job. What does the best I've found is using an SOS or Brillo pad. It really does a great job. After using one I coat the tire with a good rubber dressing.

If you've scrubbed any curbs with a tire you probably won't be able to make the lettering look right again depending on how bad the tire scraped the curb.

Also a stiff brush, water and some comet works well

I've used "Westley's Bleche-Wite" for years on all my cars. Spray it on, scrub with a stiff bristle brush, then hose it off.

If they don't come clean, they can be repainted w/ Duplicolor's Hot Tire Paint Pens.

http://www.duplicolor.com/products/hottires.html

I'll agree with Darryl.  The Bleche Wite and a rough bristle brush does the trick for me!

Standard general purpose kitchen cleaner does the job.  I used to use it on my Harley's whitewalls and it worked a treat.  Ya just gotta stop your missus from hitting you with the broom......

The whitewalls on the rear of my Harley get filthy. I have found that Comet with a still brush works the best. A Brillo pad also works wonders. I concur with the guys above.

Scott

Hell I just put a spot of Simple Green on a rag and rub each letter, works really well for me