I think the ropes on mine are each 5m long and 8mm diameter but the determining length is you should be able to take them to a winch if needed and mine are a bit short when the car is at to opposite end, so you might want to add a metre or two. Jobs easy, remove the bolt which holds the end in place, remove rope and replace. The original ropes had spliced loops but I just use a bowline to fix them in place.