need help

ok, so, I was on my way to bozmena today and on the interstate when I hit about 8- my car started to vibrate. It wasn't super badd, but it was noticable. There wasn't and shaking in the wheel, except just the vibrating. It was steady all the way up from there. It slowly kept getting worse, but never to the point where I thought anything would break. I was just wondering if anyone had any idea what might cause this. Thanks.

Its either, alignment, wheel balance, or a broken belt/cord in a tire...

I figured it was a tire issue. Thanks. I'll go get it checke out tommorrow and tell ya how it goes.

I'd go for the last one. Tire cord.