Originally Posted by
msu2001la
Good point on the 21mm internal width - it'll stretch out tires a little more than the OP's current wheels (which I think are 17mm). ...
In 2017 I bought a bike that came with Mavic Aksium wheels and later upgraded to Mavic Ksyrium Elite wheels, all of which have an internal width of 17 mm. There were still a few 15 mm IW upgrade wheelsets available. So if OP's wheels are from 2006, they are likely to be narrower.