I weigh in at 250l pounds and have been running 700x28 Armadillo All Condition tires. After 6 months and 1500 miles, my back tire had worn substantially more than the front and had to be replaced. Most of my weight during normally riding must be over the back tire, causing it to wear faster. I will probably consider 32s next time, at least for the back. I think the wider tire will distribute the weight better.