Tire fit on stock knuckle/pan rigid frame

Been out of the Harley scene for a while, and tire tech has passed me by. I'm building a bike (37 UL motor) and will be using a stock width frame. All the mm measurements are a bit confusing, even though I've seen the chart that explains it. So I'm just hoping that someone can tell me off hand what size will work. I'm really liking the Metzlers that I've been looking at.

What is the biggest tire I can get on the stock rim (16") without any interference problems. I will be fitting the fender to the bike and tire, so fender clearance is not a problem.

thanks.

Hi. I have a later model U with 16" rim stock. 130/90-16 is OK on my bike. I suppose that this will be the same on your 37 allthough yours might have 18" rim stock. The smalest clarence is on the chain. I run o-ring chain. 130/90-16 is slightly lower in height than 5,00-16.

Thank you, that will put me in the ball park. I will be using the 1937-1960something 16" wheel, and using some kind of '37-up frame...still looking for one.