What's the difference between 25-year and 30-year shingles?

25-year shingles weighs much heavier than 30-yr shingles. In laminated architectural-type shingles, the former weighs between 235 and 265 pounds per 100 square feet, while the latter weighs between 265 and 310 pounds per 100 square feet. Their thickened state makes the 30-year shingles much more durable.