get 55 series to lessen the gap....but i'm not too sure how much tread there will be when they're brand new. or else they'd probably rub.

bcuz i'm running 55 series on my back wheels which are down to 20 % tread, and i have no gap at all, whereas my fronts have 45 series which gave me a 3 finger gap. and i'm lowered abotu 2"

so its up to you man.