as the title states very briefly. would i run into any VDC or driving issues running a 245 in the front and a 285 in the rear?

 

possibly.. thats what im running (came with car) and my VDC light comes on everytime i hit a corner, like turning onto and on ramp. im trying to get smaller the like 18s

 

drop to a 275 rear or up to a 255 front and VDC should be happy

 

Correct, although the aspect ratio is the same on your proposed setup, the aspect is the percentage difference of size comparing the sidewall height to the width of the tire. Since you're proposed setup has a 40mm stagger front to rear, in this particular scenario it falls outside of the ideal overall height difference and that will upset the VDC system. Keeping it to a 30mm stagger should correct the problem.

I would recommend a 255 front if offset will allow. The size of the rims do not matter (in most cases) if you make the correct tire choices.

 

Typically put 245/30-20 and 275/30-20 with our 20" packs on the car.

 

would a 255 be to wide for a 20x8.5 with a +25 offset? I originaly had a 275 for the rear which is a 20x10 but was too strecthed for my tastes but i had a 245 up front that was flush with the rim. Am I correct in assuming that a 255 will have a slight bulge to it?