I think you mean kevlar, right? Not being a smart aleck, just clarifying Goodyear hasn't come up with some new technology I am unaware of. Anyway, kevlar, in it's generic form is aramid fiber, and is very tough. I would imagine they are using it for the belt system, not the actual tread compound. It would make the tire hard to puncture if they are in fact using a fairly thick cross section. Kevlar is used in bullet proof vests, and the helmets the US Army started using in the 80's. It's still punctureable, but would not come apart as easy as a steel belt. My day job involves custom polymer compounding that sometimes incorporate aramid fiber for wear and structural strength.
I am getting ready to put new Michilen LT's on all three of my F-150's. $592 per set. I put them on my Nissan Frontier last summer and it made the thing ride like a new care. I was amazed at what a difference it made.
I bought mine at Costco. The use compressed nitrogen to inflate the tires. The nitrogen helps keep the tires cooler and they also say it provides a smoother ride.