If you have replacement boots you can help settle this common issue
I have never pulled them off myself, but I understand there are two layers to the boots, the inside is an aluminum tube, that can not leak unless it is compromised. The outer layer is a rubbery plastic that cracks with age, but it has no role in sealing the boots.
Please take a look at your new ones and see if you can confirm this. You can usually identify aluminum because it will feel cool when you first touch it (it pulls the heat out of your finger for a second).
Many people see the cracks on the boots, freak out, and replace them - but the consensus is the black plastic is purely cosmetic.