how do u guys glue the foam strip insert together?
A light coat of contact cement/rubber cement on each surface that dries before being lightly squeezed together does the trick. Or, if you don't intend to use the insert again, put a light coat on the inside of the tire before putting in the insert- that will hold it in place.
you dont need to glue the foam insert
Generally true, but I have had a few double back on themselves, hence the techniques described above.