For a 32' long truss with 1/2" web, the limiting factor for span is not the web - it's the chords. In fact, there could be a break in the OSB in the middle, and it would not affect the truss bearing capacity much - but a break near the support points would be catastrophic. [1]
32' truss with 24" on center - 1/2" web by 16" tall - has 3200 lb on it at 50 psf, and 1600 shear at ends. Shear capacity of the OSB is 2400 lb, so we are fine on shear. [2]. We are not fine on tension at bottom chord [3]
Solution: use half inch rebar, 20' long, stapled to the bottom of the bottom 2x4 chord of the truss. 100+ staples with the rebar holds a total of 12000 lb of tension - exceeding the tension requirement of a 32' joist bottom chord - for rated design of 50 psf total roof load.
More: shear at 6' from end - at terminus of 20' mid-reinforcing rebar - is 1600 lb for 50 psf total load specification - and tensile requirement for bottom chord is 3600 lb. Quality controlled 2x4 lumber has a tensile strength of 600 psi (12 psi for ideal)

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Truss Design