Komet trailer tires

I want to replace the tires on my Komet trailer. The original tire
size is P165/80 R13, which is now hard to find.

The choice seems to be either a Firestone passenger car radial in the
correct size or a slightly taller Towmaster made by Greenball. The
trailer tire will have a taller but stiffer sidewall. It will come a
little closer to the fender, but my mechanic says less than half an
inch closer. The size is 175/80 R13.

I plan to tow about 75 mph most of the time. I really want to avoid
sway.

Any experience with these tires out there?

Thanks,
Robin RF