right when i hit around 85+ it starts to shake a little, could it be my tires(i deff need new ones). what usually causes this to happen?

well this can be a few things. one is it could be very bad unbalanced tires. and if you feel it more in the steering wheel then the body this is prolly it.

two it could be your carrier bearing on your driveshaft has worn out. if you put your hand on the center hump by the back half of the consel and you feel a very strong thump from there this is prolly the problem.

three your shocks could be bad. this is very unlikley but is a possibility. when you travel at higher speeds small bumps in the road can cause your tire to bounce up and down constantly. making a much differant vibration but a vibration none the less. i doubt this is the problem. im sure its mostly your carrier bearing on your driveshaft. or an unbalanced driveshaft. hope it helps

One thing could be you have shitty H rated tires, that would most likely happen at those speeds with H rated. Or like Mr2 said it could be a botched wheel balancing.