Cool calculator http://yojimg.net/bike/web_tools/trailcalc.php
The tire width box assumes the rim is typical 20mm width for the diameter calculation, and the tire profile doesn't have an oddball shape. For greater accuracy, physically measure the rolling distance of a wheel rotation and calculate real diameter, then plug in widths till the tire result matches. For the other numbers, find your frame's geometry page, example: http://www.konaworld.co/bike.cfm?content=smoke

Trail info can be found here.