The tire shown on the assembly line Roadster, is the FIRESTONE brand. I have a set of six - four on my '28 Phaeton, and two still in the paper wrappers.
The Firestone pattern on the 21" tires of the '28-'29 wheel, differed significantly from the later pattern for the 19" wheel of the '30-'31 tire. The closest to the 19" tire is the Coker tyre shown in Dick's post #7 It however, has too many groves on the tread.
No one currently makes a copy of the original 1928-'29 Ford 21" Firestone pattern.
I obtained my original FIRESTONE design 21" tires from a short run that were offered 50 years ago by Universal Tire Company. These were blackwall, per factory issue. At the same time I bought a set of six Double-Sided Whitewall tires, again from an extremely short run.