I have the 2.50x16 cast wheel on the back of my RetroStandard bike, with a 130/90-16 tire.  The fitment chart shows the tire is acceptable on that narrow rim (taller profile tires allow for more fitment than short profile tires).

I have no idea what size tires are available in whitewall....that is a research project for someone else!

Buying/changing tires and wheels is a time consuming and costly project.

I can't help but think this whole thing would be far easier/cheaper to buy a set of portowalls and see how they hold up!

Well my portawalls showed up today wasn’t expecting them till next week, so I was too excited and couldn’t wait so I started doing it.  First tire off and installed port wall and back on bike in 30mins the rear tire ….. well that was another story lol it was a real PITA !!! hard time trying to break the bead seal for one and then two the darn portawall kept popping out after filling with air lol after a couple hours of wrestling with it I got it all back together and set on the bike and cleaned up

What do you guys think ???