The online rebuild section says .30-.45mm so as long as I'm somewhere in there I won't touch them. (I'd rather have a factory end than one I've carved myself.) Any suggestions for a "race" setting? The tracks I'll be at are for the most part short (1/4 mile straights) but I'm hoping to visit some longer ones this summer, namely Road Atlanta. Whether or not Charles will admit to knowing me when I get there is another question...