Are Your Tires Ready for a Road Trip?

3 Simple Rules to Get You There Safely

By Patrick Rich - April 22, 2021

Your tires are the only thing that connects your vehicle and road. Everything your car does, rain, snow or shine, comes down to those 4 little black donuts. They’re kinda important. The tire is easily the most often overlooked component on a car but keeping track of your tire’s health is one of the easiest things you can do to save money in the long term and make sure your road trips are memorable and trouble-free.

There are 3 things that kill tires:

1. Wear/Damage
2. Age
3. Heat

Wear / Damage

Outside of user-induced damage (off-roading, for example), you can’t really do much to prevent damage; it’s either going to happen or it won’t. The exception would be driving a tire far beyond the legal tread wear replacement point of 2/32” of tread depth, which is dangerous for a whole lot of other reasons as well. Replace worn tires, and inspect for damage periodically. If you can see the top of Abe’s head on a penny, it’s time to replace.

Age

Age kills tires by drying out the rubber to make them stiff and brittle. This isn’t a problem for most drivers as the average driver will wear their tires’ tread out before age has a chance to retire them. Tires will begin to age out around 6 years from the manufacture date, more or less depending on the climate, and should be replaced no later than 10 years old. Manufacturers stamp the week and year the tire was made into the sidewall. Example: 3917 would have been made on the 39th week of 2017.

Heat

A tire doesn’t actually support the weight of your car, the air inside does. Properly inflated tires ensure the tire retains its designed shape to grip the road and support the weight of the vehicle. Take away that air, and the tire deforms vertically with weight and laterally around corners. In addition to faster tire wear and sloppy, even dangerous handling, the excessive flex creates enormous heat: 120 degrees Fahrenheit or more over the ambient air temperature. At those temperatures, the rubber breaks down, basically baking the tire, and weakens the internal structure of the tire casing itself. This type of damage goes unseen but can kill even brand-new tires in very little time. In addition, an under-inflated tire wears down more rapidly and reduces fuel economy, costing you money.

The best defense against this type of damage is the humble tire pressure gauge. A cheap gas station pressure gauge is okay, but something that’s easy to read and reliable down to the PSI is a really nice thing to keep in the car.

NOTE: Don’t rely too much on the manufacturer's TPMS (tire pressure monitoring system) as they are designed to alert the driver if the tires are 25% lower than the recommended pressure. At 75%, it’s already too late to prevent heat damage to tires. These are here to provide a warning of an immediate threat, not as a monitoring system for tire health.

Every car should have the recommended tire pressures on a sticker on the driver’s door jamb or in the user manual. Stick to the manufacturer’s recommended pressure. If you can’t find your manufacturer’s recommended pressures, you’ve added significant weight (fully loaded for a road trip, pulling a trailer, etc), or changed to non-factory tire size use the 10% rule to dial in the correct pressure.

The 10% rule

Start by filling to the manufacturer’s recommended “cold” pressure, before you’ve driven on the tires, or at 35 PSI for most cars and light trucks. Drive for 30 minutes to make sure they are fully warmed and stop and check the pressure again. If the pressure has gone up more than 10% over the cold pressure, you should ADD a few pounds of pressure. If the pressure has hardly changed over the cold pressure, you should drop your pressure a few pounds. It sounds counterintuitive, but if the pressure has risen more than 10% after being driven, it means the tire is flexing more than it should. This heats the air inside and causes a large change, which means adding air is the right call. Remember that under-inflating is more dangerous than over-inflating, generally speaking, so be careful when letting air out.

Keep your tires happy and your trips trouble-free with these simple rules — and keep it shiny side up.

Conclusion

Replace damaged or worn tires (before 2/32nds tread depth)

Replace tires that are older than 6 years old whether they have tread left or not.

Use the manufacturer’s recommended pressure and use the 10% rule to dial in the right pressure.

Happy trails.