Remember there is a maximum length when towing of 4.5meters.
The one for towing only needs to be rated at your cars max towing limit, about 3tonne, since for safety they are always underrated anyway, and normally need at least twice this weight to actually snap. By keeping the capacity low, you decrease the chances of damage to both your car and the one you are towing which will most likely be a lot weaker than yours should things go wrong. Bearing in mind the person you are towing may never have been towed before, so there is a good chance they may let the rope keep snatching, or run the rope over etc, so cheap and cheerful is the best option here...
For recovery, you then need a pair of nice quality (rated) straps. A long, and one short one. Our shorter one is 4.5meters, to be within the legal towing length, should we need to use it for that, for any reason.
Our long strap is 10meter, 5 tonne, there is not much point going above this, as again, taking into account the fact the strap is capable of double the rating, so potentially able to pull 10 tonnes, and at these strengths, you are now having to worry about the fixing points giving out, rather than the tow rope. Also, remember you have to make sure all your kit is at the same rating, so if you have 5 tonne straps, you need 5 tonne shackles.
I made the mistake of buying 2x8 tonne shackles to be safe, but have now switched to "Soft shackles", so we do not have the worry of heavy bits of metal flying around should things go wrong. Have a look at the size and weight of a 8 tonne shackle, scary bit of kit, especially flying through the air.
Our straps have loops at each end, in my case, one goes onto the DixonBate tow bar pin, and the other end is attached to the stranded vehicle via the soft shackle, reducing the bits of metal flying around if the cars tow point should snap. By having the 2 straps, all with loops on the end, you can easily make up a multitude of differing lengths by looping them, or joining them together, should you need to recover from further away. As we normally work on pairs, this means we can in theory have 30meters of recovery strap.
The soft shackle, is a length of Dyneema rope, with a ball spliced into one end, and a loop at the other end, so you loop it round, and put the ball through the loop, great bit of kit.
the kit I actually have is:-
4 tonne tow rope, looped at both ends. (had it years, so prob no longer rated anywhere near that.)
5 tonne 4.5m strap, loop each end
5 tonne 10m strap, loop each end
5 tonne 4m lifting loop
2 x 3.5tonne steel shackles (easier to use on cars, as 8tonne often will not pass through tow points)
2 x 8 tonne Steel shackles
2 x 5 tonne Dyneema Soft shackles
heavy pack away picnic blanket, which is used as a rope blanket when using the long straps.
Oh, and an old long Phillips screwdriver this the end ground to a ball shape, for undoing shackles, and knots in rope...
