Hopefully somebody has done this and has a good reference point to answer from:

I have a set of 7" Cookies that I want to put under my fiberglass GT flares. What size tires will fit, and when I convert the lugs to 5-lug, (via a drill and stud) will I need spacers? If so, how thick and what length studs?

245 50's w/o spacers on the 7's with about 1/2 inch to spare
I'm going with 8 inch rims and my have to file the lip of the
fender to get enough room

225's on a 7 in rim. Get more rim and run more tire.. plus a wider rim will make for more tire to the ground vs a skinner rim.ie 9 in rim with 225's will be wider than 225's on 7in rim.

Stock engine doesnt need more than 225. But I like big tires.. dont know how much tire a flare will fit, how wide of flare do you have?

Hope this helps

Andrew

225/50 x 15 all around on 7" cookie cutters ...

1 1/4" spacer in the front
1 1/2" spacer in the back

no long studs for me, i have spacers with studs pressed in.
so, you bolt on the spacer using the original studs (spacer come with steel lug nuts to do so),
then bolt your wheel onto the spacer.
NOTE: i don't have redrilled hubs, i have real 5 lug back and front.