An adjustable form is provided for building tire components of different sizes. The form includes a series of fixed length form elements intermittently disposed between a series of adjustable length form elements about the circumference of the form. The elements are movable to a first radius to form a first form surface that features first, second and third build regions onto which a tire could be constructed. Gaps, if any are present, in the first and second build regions are smaller than those in the axially intermediate second build region. The elements are movable to a second radius to form a second form surface with fourth, fifth, and sixth build regions for the construction of a tire of a different diameter. Gaps, if any are present, in the fourth and fifth build regions are smaller than those in the axially intermediate sixth build region.