My Aithein Disc is also 28 max and I doubt I could get much bigger in it (in the rear). The brake bridge is slightly too low which is the issue. Obviously all depends on your internal rim width as this will change the profile of the tire. I’m running Vision 55s (19mm internal I think) and GP5000s in 28c. Crap photo but you can see the space here:
Maybe the difference is the grand Fondo and T3 both take mudguards and long drop brakes for extra clearance.
Very nice bike by the way!!
Edit: clearance on 32s
My Aithein Disc is also 28 max and I doubt I could get much bigger in it (in the rear). The brake bridge is slightly too low which is the issue. Obviously all depends on your internal rim width as this will change the profile of the tire. I’m running Vision 55s (19mm internal I think) and GP5000s in 28c. Crap photo but you can see the space here:
1 Attachment