You don't want "really" flexible. Steele is the best rubber, however what you are experiencing is normal. Sometimes rubber takes awhile to set and conform to being squeezed. [Sometimes it may help to adjust again. Latches, strikers, hinges....or Leave doors tightly closed for a few hot days. It will get better with time
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If LMC is a less quality rubber compound than Steele and/or LMC is made in China and Steele is made in USA..........I would think the LMC rubber would be softer, not stiffer.
Me thinks you squeak too soon.
The good news is that doors close flush, right?
Some weatherstrip, on some truck models, can be put on "backwards"/wrong. I don't think I've had an old truck, with new rubber, that doors would close with light pressure.
