The tire height comment (above) is very important. In theory, the contact patch is always just enough for the air pressure to support the car weight regardless of diameter.
In practice, a taller tire is almost always better, even if you lose some effective gear ratio.
The taller tire's greater weight (like for like comparison) is also harder to get spinning and resists break-away.
Many race cars are built with the diameter of the front and rear tires as the first input, then the wheelbase.
