We weigh in as a team at 250 lbs.
Currently using the Maxxis Detonator 700x25 folding tires.
Some mileage results on various tires on our road tandem in the past 3 years:
Rear:Kenda Koncept Light: 832 miles
Front: Kenda Koncept Light: 781 miles (bulge)
Front: Maxxis Detonator 700x25 3,830 miles
Rear: Maxxis Detonator: 2,014 miles
Rear: Performance GT: 294 miles (big bulge)
front: Performance GT: 785 miles
Rear: Michelin Axial: 2,539 mile
Rear; Michelin Axial:1,295 miles (blowout)
Front: Michelin Sport: 1,123 miles
Rear: Panaracer Pasella: 2,284 miles
Front: Panaracer Pasella: 3,376 miles
This is 'real world' riding on paved roads primaraly in southern Arizona, 3 months in northern Minnesotta and and 3 months in northern Utah.
In our younger days we rode 27 x 1 1/8s or 27 x 1 1/4s; then 700 x 23s; now we have switched to 70 x 25s.
Hope this helps!
Pedal on TWOgether!
Rudy and Kay/zonatandem