I'm restoring a 70's vintage Schwinn Collegiate and Raleigh Colt, each with 26x1 3/8 tires. I purchased Kenda tires to replace the rotting originals, but have found they are a bit too large--can't seat the beads. Can anyone suggest a better brand and source?

If the size you need is indeed 26 X 1 3/8, then any tyre of that size should work.
Just make sure you don't try and mount 26 X "any decimal" size (e.g. - 26 X 1.75), because this will definitely NOT work.

you need 590mm diameter (or 597 maybe) see if it says in the size of the tire.

26 x 1 1/4 will work too, although it doesn't have that nice fat 1 3/8 look. One of my LBS's carries them, and most could probably order them.,,,,BD

I suspect the Schwinn and the Raleigh wheels each use different size tires.
Here is what good ol' tire doctor Sheldon Brown shows for these.
Do the Kendas fit either of the wheel sets?

Raleigh "EA.3" = ISO 590 mm.

Schwinn "S-6" = ISO 597 mm.

S-5 and S-6 tires are usually clearly marked as such. This is what I use for Schwinn's:
https://www.biketiresdirect.com/produ...7793231&ref=pd

This for Raleigh's:
https://www.biketiresdirect.com/searc...tf&tn=12060662

No, the tires are a bit too large for both bike wheels. I looked closer and they are 597mm, so I think I must need 590's. Thanks for your help.