I am not as familiar with the Roam 2, but when I had a look at one when I was last in a Giant dealership a few weeks ago, I would say that 50mm would definitely fit, but that would be close to the maximum, taking into account you want a bit of room around the tyre and frame. The Roam's don't have as much tyre clearance space as a Toughroad.


I think the Giant rims on the Roam have an internal width of 17mm(it could be 19mm) and so a 50mm tyre will probably measure 50mm.


I am using different rims to what Giant supplied on my Toughroad(as I wanted to go to very clyde friendly rims) and I think my rims are 23mm internal width, so my 50mm tyres look wider than 50mm to me, a lot wider, but I haven't pulled out the vernier calipers to determine it.