Before towing a vehicle _any_ distance, I'd check your local laws on this. I don't have a clue what the laws are in Germany, so I don't want to say one way or the other.
However, here in the United States, much to the surprise of many, towing a vehicle any distance beyond what it takes to get it out of the path of traffic is highly illegal. Largely due to the increased difficulty in steering and braking the towed vehicle if it comes loose. You may also find yourself on the receiving end of a lawsuit if the towed vehicle is damaged in the process. Here, we have Good Samiritan laws, but those generally only protect against being held legally responsible for illness or injury. They're not going to protect you from getting sued if you hook up to a car wrong, and rip the bumper off, even if the towed driver slams on the brakes for no apparent reason.
Like many other situations, just because many people do it, and tow straps are sold in stores, does not make it legal nor a good idea.
Also, contrary to popular belief, a strap can and will pop loose off a ball. I've seen it happen multiple times. If you're going to do this, you need some kind of positive retention at the attachment points. The hooks with the spring loaded flap is a bare minimum, and I wouldn't anything less than a screw shackle.
The other problem that you'll likely find is attaching to the TOWED vehicle. You may well come up with a way of attaching to your Tahoe, but what are you going to do about the vehicle you're about to drag down the street? Especially being the case with many modern cars, there's no good way to hook up to them on the soft front ends short of carrying frame hooks with you. The threaded holes behind the cover flaps on bumpers aren't intended to take the load of towing, they're only there to secure the car during transport on container ships or car hauler trucks.
