FAR 91.309 addresses towing gliders and requires the tow rope to have a strength "not less than 80% of the maximum certificated operating weight of the glider and not more than 200%.

It also provides for special safety links with the same requirements.

The same regulation states the towing aircraft must have a safety link with a breaking strength greater, but not more than 25% greater than that on the glider end, and not more than twice the maximum certificated operating weight of the glider.