I took my car on the expressway. I get to 70-75 no prob. But when i hit 80-85 it shakes and vibrates.

My other q is when I brake. My brakes kinda jump. They have stopping power and don't grind but they jump a little.

Thanks for anyhelp as to why I have these two probs.

The first id say out of balance tires, as far as the second, warped rotors. If they're warped bad enough I suppose it could cause vibration at high speeds but I wouldnt expect it.The next question, can you feel the vibration in the steering wheel or the seat of your pants. If the wheel, the fronts are out of balance, if in the seat, the rears. Id take the car down to NTB balance and rotate 19.99

same ? for the brakes. Replace the pair of rotors and pads that are vibrating. I wouldnt pay to have it done, you end up paying 75? labor AND 2.5 times the real cost of the parts