When my Son was in grade school I went on a field trip with him to McMinnville TN where they grow lots and lots of trees and bushes.
They grow about 20 acres of Peach trees and about 20 acres of shrubs. I don't remember the name of the shrub or bushes. After 2 years they cut the peach tree off at the roots and throw away the tree. After 2 years they cut the roots off of the shrub and throw away the roots. The shrubs are grafted to the peach tree roots. After about 2 more years they have a Bradford Pear tree.
Bradford Pear has a life expectency of about 20 years. When it gets big is self distructs. It gets too large and a strong wind or a thunder storm will blow it down. Or the limbs will get too heavy and they will brake off. Some times one limb brakes off and causes a chain reaction next thing you know one side of the tree splits and falls off.
I had 2 Bradford Pears in my front yard and one tree self distruction when it was about 9 years old. One day I notice the entire tree split like a banana peal all the limbs broke off and they were laying all around the tree like spokes of a wagon wheel.
The 18 year old tree is still growing but it has lost several large limbs and once it lost about 1/3 of the tree split and fell off. It looked pretty bad for a while but now it is looking better. Next time it looses a limb I am cutting the tree down and turning the whole tree into firewood.
I will never plant another Bradford Pear. They sure do look nice before they self distruct.