Can tires go flat from sitting? The short answer is that, yes, tires can go “flat” from sitting, and you may need another tire repair for it. However, it’s not as simple as just checking the tire pressure once and writing off the need to pay attention to the pressure for an indefinite amount of time.
A tire’s air pressure will gradually decrease over time due to a variety of factors such as:
- Exposure to the sun and changing weather conditions (hotter/colder).
- Driving on under-inflated tires may cause excessive heat and therefore increase the risk of damage to both your vehicle and yourself should you be transporting items or people in your cargo area after driving with under-inflated tires.
There are also other types of problems that can arise if your tires are not properly inflated. A vehicle’s tires contribute to handling, braking, and of course, fuel efficiency – all of which you’ll begin to lose if your tires are under-inflated.
While tires can go flat if they are sitting for a long time or have lost pressure in transit between being manufactured and installed, several factors affect the rate at which this happens.
The first is simple evaporation. A tire is not meant to be airtight, so some air will naturally come out through normal operation over time. This can be accelerated by warm weather or high humidity, which will cause the rubber compounds to expand more quickly. Still, it won’t happen nearly as fast as someone leaving their car sitting on an exposed lot during a hot summer day, for instance.
Type of Tire Compound
The second factor is the type of tire compound used in manufacturing. The rubber used in all vehicle tires is porous, allowing for air to escape over time. This rating is called the “Pascal rating” (named for Blaise Pascal, seventeenth-century mathematician), which measures how much pressure can be lost per area per hour. Higher numbers mean that the compound will hold pressure longer.
On the market today, there are three different types of wheel/tire systems:
- Standard steel wheel/tires with regular rubber compounds.
- Low rolling resistance tires with a high Pascal rating.
- Run-flat tires.
Standard steel wheels/tires with regular rubber compounds will lose air pressure at a rate of about three psi per month. Low rolling resistance tires will lose pressure much slower, in the ballpark of 0.3 psi for the same period. Run-flat tires can retain their air pressure for much more extended periods due to increased tire compound strength and design.
Like low rolling resistance tires, run-flats have higher than usual Pascals because they feature an additional sidewall liner that can meet stringent federal safety requirements. There is less chance drivers wouldn’t notice if they were leaking or punctured while driving at high speeds (128+km/h).
This sidewall protects against cuts and provides uniformity throughout the entire length of the tire cord.
The third factor is wheel/tire design. Modern standard steel wheels are manufactured to be very smooth on the inside for better tire-to-rim seating, making it likely that more air will escape during long periods of sitting time because there aren’t any cords to prevent cutting.
Most modern wheels, which feature a deep dish or step-lip design, provide enough support to hold up against everyday driving and normal road hazards such as rocks and potholes (that don’t penetrate deep into sidewalls).
The interior of these wheels can be porous and cut easily if something pierces the outer layer. On the other hand, because of these designs, wheels with step-lip and deep-dish styles are more likely to hold air pressure longer than standard steel wheels.
Most alloy wheels (which are made up of an inner and outer layer bonded together) feature a deeper dish design that prevents the tire from sliding down into the well, reducing the contact patch and allowing for more tire roll when cornering at high speeds.
However, alloy wheels can still be porous due to their construction process – a two-piece design features a separate face cap welded onto a tube containing rubber gaskets, each of which can let some air escape if punctured or compromised by hot summer weather conditions. Alloy wheel liners can also develop cracks during manufacturing or from road hazards.
What if I use Nitrogen?
Nitrogen remains contained in tires longer because it does not expand or contract as much as air under changes in temperature. This nitrogen quality allows tires filled with the gas to maintain proper inflation pressures longer than those filled with compressed air at sea level.
The difference is significant enough so that properly inflated nitrogen-filled tires typically need re-inflation several times less frequently than their compressed-air counterparts. According to the International Association of the Rolling Industry (AIR), “Nitrogen is completely stable; it doesn’t support either oxidation or corrosion. Oxygen, by comparison, would make steel brittle very quickly. Nitrogen also helps retard water in tire cavities that could cause rotational force variations.”
So, while nitrogen will prevent the air pressure inside your tires from going “flat” due to exposure to oxygen in the atmosphere, nitrogen leaks can still occur over time due to some other factors such as an accident on some certain types of wheel rims.
In summary, if a tire is sitting in an exposed lot for extended periods, it will lose pressure faster than one driven regularly. If a modern standard steel wheel features a smooth interior and exterior, it can be more likely to leak air because there aren’t any cords to prevent cord slippage – making it easier for the tire beads to slide down into the well.
In comparison, alloy wheels are usually better for retaining air pressure due to a design that prevents tires from sliding down into the well and their deeper dish/step-lip, which increases contact patch size.
Run-flat tires can retain air pressure much longer than standard steel wheels because they feature stronger sidewall construction and increased surface area from thicker sidewall construction, which prevents cuts and punctures. When you have a flat tire and need tire repair, check out the tire repair service center’s website before bringing in your vehicle to ensure they are a trustworthy business. Click the following link to see what the website of a reliable tire repair company looks like: goodtirecalgary.ca/tire-services.