This sounds like a classic case of insufficient toe-in (Different from too much
toe-out.)
Here is how I do it:
Get some 2" masking tape, a big block, a ball point pen or sharpie and wrenches
to adjust the center rod.
Jack one front wheel clear of the ground. Run a band of tape around the center
of the tread, all the way around to where it overlaps some. Using the block
and the marker or pen, hold the point very steady against the center of the
tape while you turn the wheel, making a mark on the tape. If it doesn't meet,
try in a different place until you get a good straight line all the way around.
Let the wheel down gently and do the same on the other side. Measure the
distance between the lines on both wheels in front and in back. (a helper is
most valuable here.) They should be from 0 to 1/16" closer in front than in
back. If not, adjust the center rod until they are, remembering that as they
get closer in front they get further in back so it changes pretty fast.

If you found it wider in front than in back, ¡Bingo! That was your problem.
If not, the different tires may require different alignment parameters and I
really don't know what they would be. IPD can probably give you guidance on
this because they have sold a LOT of specialty wheels through the years and
helped the buyers get them to work right.
--
George Downs Bartlesville, Heart of the USA!