By far hardest decision ever!!!!!!!!

Backspacing is the crucial component when fitting a rim.
Spacers are needed when a rim with improper backspacing is used. Since you are starting out with a blank slate, I recommend selecting a rim with the correct backspacing.

If you are going to maintain your factory brakes I would suggest a 15x7 rim.

See below link pretty good wu on wheel sizes

http://www.mustangmonthly.com/techarticles/mump_0507_ford_mustang_large_wheels_fit/

my favorite "stock" rims are magnum 500s
14's

Truer words never spoken!

milstang31 said:

Hello everyone, Im at that point in my restoration to be thinking about wheels and tires , first I was wondering the largest size wheel I can put on my '66 (stock brakes) without purchasing the adapters. I was also wondering if anyone would be kind enough to post pictures of their '66 (or '65, '67)wheels.

Thanks a lot

Click to expand...

The more pictures you can look at the better off you will be. Look through the galleries, and also where guys have posted car show/track day threads.
IMO, it really depends on what the overall premise is, and part of tires and wheels directly relates to the stance of the car. You can buy the sweetest tires and wheels, then have the car too low or too high, or front/rear too low/high.
When in doubt it is hard to go wrong with a set of 15" replica Torque thrust wheels.
On the website in my sig are some pictures of the GT40 knock offs (unfortunately better known now as "Eleanor wheels" ) 17x8 4.75"B.S. 235/45 tires. Front stance is nice, rear is too high (IMO). Need to narrow rear before going any lower in the back. The car will eventually have G.T.350 striping with no fender badging. I didn't want too much flash taking away from the other wise clean lines of a G.T.350. and thought these would blend in well.

Good luck,

"D"'s

http://forums.stangnet.com/attachment.php?attachmentid=43879&d=1144471021

Hook are those yours? whats the sizes/tire combos? I like the look.