Spare in my '67 is a piece of junk too. Only had to use it once - and not at highway speed. D78-14
Used to be I could be decent used tires, mounted and balanced for $15-25. That was OK when driving a $300 DD and also autocrossing it. But those days are gone, and I also learned that half worn tires are much more subject to getting flats.
Go get some decent tires. They'll improve braking, and cornering, and maybe acceleration a little if you've got the touch.
View attachment 1715532744