SAN DIEGO -- In two-and-a-half-years, almost 500 tour buses have been placed out of service in California, Team 10 learned.
The information from the California Highway Patrol's Motor Carrier Safety Program shows after inspection, more tour buses were placed out of service through six months of 2016 than all of 2015.
The CHP's inspections are broken down into two main categories: off-highway and on-highway.
Fewer buses have been pulled out of service during on-highway inspections.
Thirteen people died and 31 more were injured when a tour bus plowed into a big-rig near Palm Springs Sunday. Earlier this week, National Transportation Safety Board investigators said several of the tires on the bus were worn out and unsafe.
The numbers that the CHP sent to 10News show there have been nearly 600 tire and wheel violations out of 15,000 tour bus inspections statewide in the past two-and-a-half years.
However, investigators don't yet know whether tires were an issue in the Palm Springs crash.
It's going to take some time before the NTSB has concluded its investigation into what caused Sunday's tour bus crash.
