are those 10.50s on stock wheels? you're not going to be able to run 33s on stockers. my steelies (15x8) are at 4" of BS which i like. regardless of what size tire youre running though, it's easy to fix the rubbing against the front leaves. do a search for "steering stops."
again, if you would use the search feature at the top of the page you could answer these questions for yourself (it's all been asked before, i promise). BS refers to the distance (usually in inches) from the mounting surface on the inside of the rim to the outer lip of the rim. more BS means the rims will sit closer in towards the body of the jeep, less BS will put them further outside the flares. so, BS isn't a physical item you can install. you may be thinking of wheel spacers which allow you to move your wheels further outside of the flares, which are as easy to mount as removing/installing a tire.
Im running 15x10 wheels with 3.75" backspacing. I am running 35x12.50 tires. I wouldnt go with less back spacing because the tires come pretty close (within about 1-2") to the front springs. they will stick out, so be prepared to get some wider flares. Also, if you go with less backspacing you may have clearance issues with the extended brake lines if you are lifted. Less backspacing is good though, the wheels tuck when articulating.