what wheel and tire size gives you nice look and performance 15,17,or 18

 

Personally I like 15's or 16's but its going to be up to the owner what looks best. I think anything over 16 on a classic is pushing it and can also hurt performance...

 

Look is subjective, so I won't touch it.

Performance is dependant.
Dependant on your definition of performance.

Wider tires offer better grip
Smaller sidewalls offer decreases in lateral deflection (aka improved cornering)
Tall sidewalls with lower air pressure sometimes offer improved footprint and launch (depending on the tire type)

So what kinda performance you want?

 

But wide tires could also hurt you by creating more drag, correct? I put 275's on my 98 and easily noticed its slower[:'(]

 

Yes, if you put too much tire on your car it will slow you down.

 

yup wider tires will hurt gas milage because that is more friction but paired with a lower profile tire can make a very good car because of the less deflection you can take very corners like no other and it helps with handling but as said b4 the taller sidewall would be better for straightline performance and personally i think 17" rims are the limit lol i have seen 30" rims on vehicles here and its nasty but 17 is ok if done right

 

IMHO I like 15X7's combined with a decent sized tire, I hate ginormous rims and bandaids!

 

I just put on 15x8's, most if not all classic mustangs came with stock 14" rims you could get the optional 15" if ordered .

I agree anything larger than 16" will cross you over to Hooptie Land where the car will graduate to the rank of the old big body chevys & buicks...... Then you would mount the 24" woofers in the trunk....