Cool. Hope they work out. I found them by Googling for "1/12 scale Ferrari". I have the Revell/AG Ferrari F2002, and I could have sworn that I saw A/M sets of tires also, but I forgot where I saw it. Thought it was through Squadron or GM, but a search on both turned up nothing. Maybe Antares can help you locate the tires.
You also might try contacting Revell to see if they will sell you just a set of replacement tires for that kit. (I'd be curious to know myself).
Their homepage address is www.revell.de
or, you can contact them at this address:
http://www.revell.de/typo3/en/contact/index.html?&L=1
Also found this link for R/C tires:
http://www.bsr-racing.com/prolite.htm
The BSR tires are rated in temp ranges (as if that really applies, eh?) by color. I know nothing at all about R/C racing, but just looking at the pics, they all appear to be black. Anyway you can call them and find out.
Good luck. Let us know how it turns out.
Hope this helps,
stinger