Title says it all... can i get away with going with a 140/90-16 for my rear in lue of a 130/90-16 (as i cannot fine anything but bias ply). My front tire is a 110/90-19 can I get away with a 110/80-19 or something of the sort? I know these bikes were built around bias ply tires, but I...

New bike owner here so I appreciate any help/advice you may have. I have only been able to find one rear tire that matches what is currently on my 81 gs450, 110/90/17. My commute will be about 45 min each way at highway speeds so I'd really like to get the nicest tire I can and not be stuck...