Q: 2009 Toyota Tacoma - There is a lot of shaking/vibration in the steering wheel when driving at speeds of 55-70 mph

Many Toyota wheels are lug centric. That means that an adapter plate has to be used to center the wheel to the balancer through the lug mounting holes and not through the hub pilot hole using a conventional centering cone. What you should first do is find a shop that has the adapter plate; they are common and, indeed, if you refer to lug centric balancing in your conversations at the shop but they do understand you, do not get your tires balanced at that shop. Once the assembly is correctly mounted with the adapter plate, balance the assembly. Remove the balanced assembly from the balancer and re-index it (say 90 or 120 degrees) on the balancer. Re-run the balancer. If the assembly is not still balanced the machine is not calibrated, or the assembly was not properly mounted. The default on the balancer, of .25 ounces, can also be overridden by the operator to see what the actual imbalance is. Prior to doing all this, unless the wheels are brand new OEM Toyota wheels, measure the wheels for run out, perhaps as installed on the car as you need to see if there is any hub runout, too. Once the wheel/tire assembly is balanced per Toyota’s instructions (lug centric using the adapter), if the problem persists, you will have to have the wheel/tire assemblies run on a road force balancer which will tell you if the vibration perhaps stems from excessive radial force variation in the tires. This is very critical. I once bought a brand new set of Consumer Report’s highest rated tires. Despite multiple, repetitive intense efforts at balancing that brand new set of tires, they vibrated like crazy at highway speeds. It turned out the tires had a radial force variation in the sidewalls which was only understood after replacing them with a brand new set of Michelin tires. A conventional balancer will not measure radial force variation. The vibration immediately disappeared once the defective tires were replaced. A point is the wheel/tire assembly must be ruled out as the cause of the vibration. Once that is ruled out (lug centric mounting, re-indexing, measure radial force variation, axial and radial wheel run-out), if the problem still persists, that means that the suspension/steering system has a loose (worn) component, or the problem exists elsewhere as defective motor mounts or imbalance in another rotating assembly. If you want the vehicle inspected to get this resolved, please request a vehicle vibration diagnostic. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you, particularly if you just need more information to make a wise, informed decision.