WASHINGTON - As the fall and winter driving seasons get under way, the National Highway Traffic Safety Administration is urging users of 15-passenger vans to take specific steps to keep occupants safe. Two recent fatal crashes, in New York and Georgia, involving 15-passenger vans that rolled over and resulted in 10 deaths give urgency to this reminder.

The agency warns that tire maintenance is paramount to preventing tragedies, such as these recent rollover crashes, from occurring. Users of 15-passenger vans need to make sure the vehicles have appropriately sized tires that are properly inflated before every trip. The agency also reminds owners that tires degrade over time. For this reason, NHTSA recommends that spare tires not be used as replacements for worn tires. In fact, many tire manufacturers recommend that tires older than 10 years not be used at all.

In particular, NHTSA said it is directing this advisory to church groups, other non-profit organizations and colleges that may be keeping older 15-passenger vans in service longer than usual because of tight transportation budgets. Pre-primary, primary and secondary schools should not use 15-passenger vans for transporting school children, since they don't provide the same level of safety as school buses, NHTSA said. It is also against federal law for schools to buy new 15-passenger vans for school transportation purposes.

Here are some safety tips for 15-passenger vans:

• Make sure the vehicle is properly maintained.

• Make sure drivers are fully trained and experienced in operating a 15-passenger van and are properly licensed.

• Never overload under any circumstances. Agency research shows overloading not only increases rollover risk but makes the vehicle more unstable in any handling maneuvers.

• Make sure that properly sized tires are being used.

• Before every trip, drivers should check the tires for proper inflation and make sure there are no signs of wear. Correct tire size and inflation pressure information can be found in the owner's manual.

• Make sure all passengers buckle up for every trip.