The spare tire detached from its mount under the vehicle while we were driving at highway speed on i-76 in ne colorado. the tire fell to the pavement and was struck by the travel trailer we were towing, blowing out a trailer tire and damaging the trailer. the spare tire was struck a few minutes later by another vehicle, causing failure to 2 tires on their vehicle and near loss of vehicle control. the people in the second vehicle confirmed it was our spare tire. at the time of this incident, our toyota tundra was 10 months old, purchased in january 2017. the spare tire had never been used nor had it been lowered or removed from its factory-installed mounting device. it was fitted with a dealer-installed spare tire lock. the truck has not been in an accident or damaged in any way and has been maintained by the dealership where it was purchased. we have a dash-cam file of the incident but it only shows that nothing else was in the highway as the incident occurred. the rearview camera only shows the travel trailer rocking as it went over the spare tire.