Posted December 28, 2011 - 07:27 PM
I have made sets of chains many times over the years, from truck tires, to tractor tires, to lawn tractors and snowblowers. We used to have a chain cutter and press on the farm and just made them as we needed. Its not hard to measure up. Generally i like the chains to come down a couple inches onto the sidewall. For example 23-4=19" diameter, thats subtracting 2 inches for each side from the diameter. Take 19" diameter and convert to circumference and thats 59.6 inches. I would go with 60 inches at least if your using the standard type hook for fastening. I made some with carabiner's before for the outside and plain hook for the inside and then just criss cross some bungie cords to take up the slack. You could also add an extra link or two beyond the measurement just for adjustment needs.
For the width of the chains it would be the tire width plus the distance it extends onto the sidewall of the tire on both sides, so 8.5+2+2=12.5". You don't have to be perfect on all these measurements, just cut to the closest link.