Determining weight capacity of tires
I have a friend who wants to repurpose a bike as an errands bike; he has plenty of shops in a tolerable radius. The bike is a custom-built (by Bilenky) upright tourer and for various Euro trips he has moved on to other bikes. The Bilenky looks right, and is equipped with a Rohloff hub (for this entire bike, $$$ doesn't begin to describe it, more like $$$$$$$); plenty sturdy and has all the right bits for brakes, etc. And he wants to electrify it. So far -- cool. Alas, he's worried about weight capacity: the bike is something like 38LB and you have to add in the electric conversion, plus the cargo load, and he's a pretty big guy. So, before he starts throwing money at the project, is there a way to determine what the weight capacity is of a given tire? For instance, he rides on Continental's GP5000 and also Gatorskins on other bikes, so I hit their website -- all kinds of info but no max weight capacity (like a car tire would). The bike is on 28mm tires now and a rudimentary check shows 35mm no problem, not so sure about 42mm. Any thoughts on how to calculate whether he can do this?
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Larry:1958 Drysdale, 1961 Gitane Gran Sport, 1974 Zeus track, 1988 Masi Gran Corsa, 1974 Falcon, 1980 Palo Alto, 1973 Raleigh Gran Sport, 1974 Legnano. Susan: 1976 Windsor Profesional.