Thanks, but generic calculators aren't correct for most tire manufacturers. So again... If it's 30 mm diameter shorter, than it would be half each direction from the axle, so 15 mm lower. Tough to repeat myself here.Todd, this is what I found on line, its saying the difference is 30mm in the diameter. So the 60 series will in fact lower the rear of the bike by 30mm which seems a lot...
You need to get the tire info from the manufacturer to compare accurately.