My rear marathon plus is running around 3k miles. Bad roads, heavy heavy rider plus gear and hard riding. The center is flat where the tread used to be and is pretty squared off.

This is my first marathon plus all my other tires had worn through to the cords, rotted or got torn up by the road. I'm worried I might actually be or soon be riding on that smartguard layer shown in blue here (is it really blue?):


Here is the front tire and you can see the treads

Here is the rear tire and that little circle I think is from that nail I dragged around for a couple days a while back I just pumped it back up to 95psi.


I already have a new tire or two ready to go. Could they be worn out to an unsafe level or a slow me down too much level?

Edit: They are really blue I cut open the one I broke the bead on. It looks like I could ride till I get to the blue smartguard layer but should I swap them out before then?