29rs on 700c?
 

I've got a 2020 Giant Roam. I'd like to put some 29" MTB tires on the bike. Question: WOuld anyone happen to know the max width I can fit on the bike?

The technical term for the spec you are looking for is 'tire clearance'. A quick google search on "tire clearance giant roam" give you 55mm/2.2in, but it's probably the current version, not the 2020. (I'm not allowed to paste links, not enough messages)

Otherwise, the is a discussion on this forum called "giant roam owners largest tire option" were 47mm seems to be a good consensus. The thread is from 2018, so it might be different you. (Again, I'm not allowed to paste links, not enough messages)

Just bear in mind that you need to leave some space for muds/rocks, and that the measurement in the specs only gives the diameter, not the shape of the section. Some knobs make the section of tire more "square", so you can limited by that.

I had a 2018 Roam and found that 29x2 tires fit reasonably well. I actually had two sets of tires on it -- 29x2.1" WTB Nanos and 29x2" Schwalbe Hurricanes. Both fit well, but are probably as large as I'd have been comfortable with.

Remember that a larger tire like this will raise the height of the bike (frame, bottom bracket, top tube, etc.), so make sure you have enough standover clearance if you're concerned about that.

oh I see what your bike is now. beefier than my old Trek FX Alpha 7.0