Steering wheel first button added to the steering wheel was a switch to activate the car's electric horn. Traditionally located on the steering wheel hub or center pad, the horn switch was sometimes placed on the spokes or activated via a decorative horn ring which obviated the necessity to move a hand away from the rim. Electrical connections are made via a slip ring. A further development, the Rim Blow steering wheel, integrated the horn switch into the steering wheel rim. In 1966, Ford offered the Highway Pilot Speed Control Option, with steering wheel pad mounted rocker switches, on its Thunderbird. Uniquely,
Tire Wear bars (or wear indicators) are raised features located at the bottom of the tread grooves that indicate the tire has reached its wear limit. When the tread lugs are worn to the point that the wear bars connect across the lugs, the tires are fully worn and should be taken out of service. Most wear bars indicate a remaining tread depth of and are tires are deemed "worn out" when the tread is worn down to that point. The tire bead is the part of the tire that contacts the rim on the wheel. The bead is typically reinforced