Inflatable Obstacle Course Tire Set. Running an obstacle course for this year's field day? Inflate these vinyl tires for a challenge kids are sure to love! What fun, kids can walk, hop or jump through these inflatable tires to get to the end of the course! Not just a good exercise, young athletes will improve overall coordination and balance as they practice on their skills. These obstacle course tires come in blue, red, purple, green, orange and yellow. Tires have a 21" diameter with an 11" opening. (6 pcs. per set)