Clydesdales/Athenas (200+ lb / 91+ kg) - How wide can I go?

I've recently gotten back into riding my mountain bike with slicks to try and get down for this all time weight high I'm at. I bought myself a Centurian LaMans a year ago with the intent of finally riding a road bike (been dreaming of it for years) but I never did.

Now that I'm biking again, I'm working up my endurance to ride the LaMans. While I'm working on my endurance, I figure I might as well make the LaMans more Clyde friendly. I'm putting cage pedeals on since I don't like clip in's. I'm thinking about buying a Brooks saddle, I also want to replace the tires with wider tires. Currently there 23mm tires on the bike. I'm looking at putting on 28mm or larger tires. But, I'm not sure what my limiting factor will be. I am thinking that the brake's will limit how wide of a tire I can put on? I'm not sure how wide I can adjust the cailpars to accomidate a wide tire. Is it the frame/fork that will dictate my max tire size? From what I've read, I'm pretty sure i can put on 28mm tires with no issues. I would like to use a ~32mm tire if possible.

I know this is kinda a clyde/mechanical question so I'm not sure I've asked it in the right forum. Hopefully I did.

In part, the clearance at your fork crown and brake bridge will determine how wide you can go. (for the frame)

More importantly is the rim itself. You don't want to put too wide a tire on a narrow rim.

Sheldon Brown's Tire Sizing page (http://www.sheldonbrown.com/tire_sizing.html) has a chart (near the bottom) with the safe combos of rim width to tire size.

On my Schwinn Tempo I couldn't even put 28's on without them rubbing. The Centurion has more clearance so 28's would probably fit, but there is no way that 32's would fit.

With my older Trek road bike, I'm lucky to get 28mm tires to slide past the brake pads. Height-wise there's more room, but anything larger than a 28mm simply won't squeeze past the brake pads.