Don't need it but I like peace of mind
I have forgot to strap the back tire in hundreds of times. In my experience you really don't need to unless SHTF. But in any case these do give you a peace of mind and some security knowing your back tire isn't going to come fly off the side of your car suspended by your fork. Needless to say these keep your bike secure and are simple to use. Over time the clasps stick a bit and or if you cinch them down to much the same thing will happen. Some of the teeth do wear out over time, but hell I have had my viper for 10 years now and I still have the original. All in all I really like this product super dependable.