I think this is the trick to white or silver grilles, leave the surround grey or black(I have a suspicion that body matched would not look good) and paint everything inside the front edge white or silver
Yeah those GYs are freakishly light for what they are, I've not seen any tire in either size (285/70R17 and 315/70R17) that even comes close to the OEM GY territory MT, my guess it they are not going to last and/or puncture easy, you can't just make a tire 10 or 20lbs lighter without giving up...
something like this in front of the seem should work https://www.hyperflight.co.uk/products.asp?code=F-RMXTT1&name=turbulator-tape
a simple narrow like .5-1mm thick strip tape might work too