Converting a Smallframe Vespa to a 3-inch rear rim with a 120/70-10 tire is a relatively complex process and requires, among other things, extensive sheet metal and tinning work, which we regularly carry out in our Vespa workshop:
The 3-inch rim required for the conversion to a 120 millimeter wide tire creates a track offset, as the wider tire has to be spaced away from the engine - this offset is compensated for by a corresponding shortening of the engine crossmember, so that the engine is ultimately positioned further to the right in the frame.
This necessitates widening the right side panel - for reasons of symmetry, both panels are therefore separated from the frame, widened, then welded back on and finally tinned - the position of the rear shock absorber, which is tilted due to the engine offset, is also corrected.
Finally, in most cases the exhaust system also needs to be modified and readjusted to fit the wide tire - our hand-built exhaust systems are of course designed for use with a wide tire right from the start.