Newbie questions about our Trek T900 which has been fairly heavily modified from stock by it's previous owner. It is time to replace the tires and I would appreciate some guidance. Currently it has NOKIAN Rollspeed AWS slick tires in size 26 x 1.3 / 37-559 on Alex TA19 rims.

We use this bike exclusively for short (<30 km) urban bike roads, during fair weather, on city roads and paved cycle paths. We weigh about 340lbs and typically only have lunch and an extra sweatshirt in the panniers. We also often pull a child on an Adams Trail - A - Bike, or have a Burley trailer with cooler/fishing equipment. So you can see there is no hardcore touring going on here.

My primary concern is safety, followed by durability and cost. I am not at all concerned about getting the thinnest, lightest, tire possible to save a few grams. I'm quiet happy to having something durable and reliable even if it means a somewhat heavier tire with higher rolling resistance. Having said that the Nokians have served us well. We'd be happy with another pair but they seem a little difficult to come by here in Toronto, ON although I'll admit I've only just started looking.

Also, can I safely put a 1.25 or a 1.5 tire on this setup, as long as I stick with the 26" diameter. They seem to be a far more common width. Having said that, the Nokian AWS seems to be available in 1.3 and 2.0 sizes. Would it be crazy to go up to a 2.0 on this setup, if it even safely fits, for added stability and cornering etc.?

Thanks for any and all guidance.