Run-flat inserts from Armormax® are not like conventional tires, which require air to stay hard. The run-flat tires have a reinforced sidewall that allows these tires to stay rigid without any air pressure.
Actually, they are designed to remain functional for a limited time without air pressure. On our heavy-duty inserts sometimes called an Armormax® donut can even be used without the existing tires on the vehicle.
The reinforced outer shell of run-flat tires keeps the rubber in place without air. It also supports the car to continue its journey. However, the sidewall of run-flat-tires is not designed to be permanent and is only recommended for around 50 miles of additional driving after the tire has deflated or shot out. To keep run-flat inserts and tires in good condition you have to check their depth, pressure, and condition often.