The problem you may encounter with tire sizes of 28mm and greater is brake clearance when mounting your wheel. It may not be a problem if you are willing to mount wheel first then inflate tire. Only a problem when repairing a flat or doing maintenance. We've done some "medium" loaded tours on 25mm's. They worked OK. We have also done quite a bit of "fully" loaded touring using 28's, including a "trek" across the US.