Will I rub ?

I have 215/40/17 on my civic.

will i rub if i lower my car 1.75"? if yes, how low can i go without rubbing?

You shouldnt rub with only 1.75" but 215's are a little wide for a civic. My brother had 215/40/16 on his civic with a 2" drop and we had to end up cutting off the lip on the inside of the fender so they wouldnt rub anymore. You might have trouble with turning sharp corners tho.

yeah, i know.

actually i have coilovers on right now, and the fender gap is about 2-3 fingers high...and it rarely rubs. but i want to change to springs, and i just don't know how long i should go to get the same height.