What size drag radial to put on stock 18" rims?

245/40/18 Mickey Thompson ET Street Radial.

Or try to drop down to a 17" wheel

Thanks for the reply. I would love to go to a 17" rim, but the Brembros won't clear. Do you happen to know what size tire to run on the front, I figure I'll just run stock size whatever that is for the 18's.

i'd run the stock tire size up front...

You might consider a set of used Evo 8 17's that will fit...Can find them for $400 for the set. They're lighter, tires are cheaper, and they'll perform better on the strip