weather front
The reason is, that it is recomended, in the manual, to leave a section in the middle of the rad. mainly for the air exchanger. you'll never see big rig, unless really cold with his rad. complety covered, yes air, will get in and around in to engine comparment, i stated 40 sq in. thats realy about 6 1/2"x 6 1/2, not that much, i think mosyly to work with the air exchanger. most of the weather guards don't cover up the openings in the bumper either. but you can do this if you want, i just happen to have the covers to do this on mine, it helps a little on warm up, temp does'nt get any hotter. this is, just the way that i decided to do it, I hope that this has been some help.
Marv.