A larger treaty fleet would expose Germany's infrastructure ceiling

How would a Tillman-style Washington treaty change German capital-ship strategy?

It would make German surface ships less competitive and could drive an earlier shift toward a predominantly submarine navy.

Germany's binding constraint was industrial infrastructure rather than the enlarged Washington limits enjoyed by the other powers. A larger British program could provide pairs of fast capital ships able to intercept Scharnhorst- or Bismarck-type raiders before a small speed advantage became useful. Repeated surface losses might push Germany toward a submarine-only strategy earlier than it did historically. That shift could intensify the U-boat threat while freeing British heavy units for the Mediterranean and Indian Ocean. The counterfactual therefore changes both the surface balance and the allocation of Royal Navy forces across theaters.