Yes you hire an attorney . There is no guarantee that an attorney can prevail , but your chances are better than if you handled it yourself .
Normally, a speeding ticket of 70 in a 55 might be something that traffic school can clear and therefore remedy one from losing their driver's license. However, if it were filed as a reckless driving misdemeanor or you have suffered too many points in a particular time period, the Dept of Motor Vehicles may arguably look to suspend your license. And in that case, you should seek out counsel to fight the ticket. You should understand that there are no guarantees of success but a knowledgeable traffic attorney will have a plan of attack that might give you a chance.
This does not constitute legal advice and does not create an attorney-client relationship but is merely a general discussion of legal principles based upon a hypothetical.