Your tires are probably off balance or need to be rotated. I feel like a nerd knowing this but my boyfriend is the assistant manager at discount tire so i hear about tires and stuff all the time haha that use to happen to my car and he balanced them and what not and rotated them i think and then it was fine. I would go to a tire place and ask them but thats probably it

It shouldnt be to expensive at all if that is all that it is