If you're going to keep the car a while, it might be a good program. My GS430 is on it's 4th set of tires in 80,000 miles. Of course, it came with some, so I've replaced the tires 3 times and I'm about to have to change them again. Each time I replace the tires, I spend around $800 - $1000 all in. And, I've had my rims repaired once (wife rubbed them up against a curb...).
If I could go back and pay for such a program, I would - depending on some of the good points made earlier (e.g. what tires are included, what are labor costs for installation, etc...) but then again, I've driven my car almost 80,000 miles and counting.