'Old school' Honest Abe is a reliable test for determining tire tread depth. Insert a dime between the tread blocks with Abe's head facing you upside down. If you can see the top of his head, your tread is too shallow and needs to be replaced.
In the past, I’ve always just gone with whatever my shop of choice has recommended, which was usually just to replace them with a newer version of whatever was already on the car.
Thank goodness for Tire Rack. Their Tire Decision Guide helped me think through what my tires truly needed to be capable of. It even made some recommendations based on my location and average climate.
They called once they received the tires and we made an appointment to have them installed. It was a win for us because being nomads, we’ve come to love the ease of using Firestone Complete Auto Care, which we were able to use to install our tires.