When it comes to cars, there are many aspects that we need to maintain so that they serve us as long as possible. Doing regular oil changes and replacing consumables are only half of the story when discussing proper maintenance.
It’s the same thing with the tires. Some people get a new set, install them, and forget they exist. They don’t maintain or check them through their lifespan and blame it on poor manufacturing. The reality is that it’s the result of poor ownership, but that’s not what I’ll be talking about.
Today, I’ll talk about the people who regularly maintain and check their tires and want to keep them in the best shape possible. Some of them aren’t versed in this industry, and there are some things they’re not sure of.
A common thing most people are confused about is the tire’s shape. Specifically, I’m talking about the tires looking flat despite being inflated at the optimal pressure. There are several reasons, and I’ll explain each one.
Most of them are nothing to be concerned about, but it’s good to know the story behind them. For the sake of this guide, I’ll explain this if you’ve already checked the pressure and you’re 100% sure that it’s the one from the sticker on the door sill.
Why do tires look flat?
When parked, your car seems to have 4 slightly flat tires, and that’s normal. Modern tires are designed to have some flex, something we often mention in our reviews. As you’re driving, there is some movement in the blocks, but there’s also some movement in the sidewall.
We notice this when driving, but it’s also noticeable when your car is parked. The car’s weight pushes each corner into the ground and slightly flattens the bottom part, and it’s something you shouldn’t worry about as long as the pressure is optimal.
Many people will say that it’s a side effect of the construction and materials of the tire, but this is by design. If the tire has a perfect shape and has no flatter area under it, then the contact patch will be smaller. As a result, you won’t have the necessary grip and traction for a safe driving experience.
The slightly flat area we call the contact patch is the area that’s responsible for the overall performance of the tire. It helps offer higher levels of grip and traction than it would have if it were perfectly round.
With this in mind, you should know that it’s normal to see this, but now let’s talk about two situations where it’s not normal and what you can do to prevent that.
Situations when seeing a tire looking flat aren’t normal
For the most part, seeing your tires being slightly flat isn’t something to worry about. With that said, there are situations when it’s problematic and may lead to long-term damage, which can reduce the lifespan and compromise your safety.
Leaving your car parked for longer periods of time can result in a little thing called flat spots. This is where the car has been sitting for so long that the rubber and construction are deformed, and there is literally a flat part on the tread. Keep in mind that it should be round.
We see this commonly with people who put away their “fun” cars in a garage over the winter. I never really understood that concept, but I won’t go into details about it. The cars sit parked for months, and the weight slowly deforms the tires. Throw in the fact that tires lose a bit of pressure over time; you may be looking at flat tires by spring.
To remedy this problem, there are two things you should do. The first one is to keep the pressure as close to the optimal as possible. A portable tire inflator does a very good job for home use and will be an excellent tool to keep the tires always inflated properly.
The second thing you should do is to move the car around. Just as most mechanics recommend starting the engine occasionally to remain healthy and happy, any tire expert will say the same for the tires.
You don’t have to drive the car for miles; you parked it in the garage for winter storage, so you probably won’t move it anywhere. A few rolls forward and back should be enough for the other parts of the tires to see some weight. Also, it’s a good idea to ensure the car isn’t parked in the same place, because you’ll be putting it on the same area of the tires you want to avoid.
Ideally, you’d want to drive a bit so that the tires roll a bit and hopefully return to their original shape. If you can’t do that, then at least try to roll your car and leave it parked in a slightly different location.
The second reason you’re seeing tires that look flat and are not underinflated is due to weight. During development, car manufacturers take tire size and vehicle weight to determine the best pressure. They look at loaded and unloaded cars, which is why, in some situations, you may see different tire pressures depending on how much load or passengers you have.
You may notice your tires sitting flatter than usual if you have a massive load in your trunk or 3 people in the back seat. The “flatness” will be more pronounced on the back because that’s where all the weight is, while the front should be more or less the same.
The solution is to either reduce the load or inflate the tires accordingly. Some cars won’t have this info, so your best bet is to talk to your local tire technician and see how much psi over the “optimal” you should go. Keep in mind that once you’re back to the standard load in the back, you should drop the pressure to the normal one.
Why do some tires seem flatter than others?
You probably think all tires look equally flat when sitting on a parked car while inflated at optimal pressure, but that’s not the case. There are many reasons why tires on one car will be flatter than on another. With that said, maybe even two sets of tires on the same car will look differently flat, so why is that?
This is where the type of tire comes into play, especially the internal construction. Tires designed with performance in mind often have stiffer sidewalls and less flex when compared with something like a touring or winter tire. Comparing both types with the same dimensions, you’ll notice that the UHP tire will look less flat when compared with the other types.
It’s the same story with run-flat tires. They are designed with reinforcements to keep the car’s weight even when there’s a blowout, so these, too, won’t look too flat.
The second aspect worth mentioning is the tire size, specifically the sidewall profile. You probably know that there are tires with different heights, some with higher sidewalls while others have lower ones, which we often call low-profile tires. The difference in sidewall height can make a tire look slightly flatter than another if the profile is bigger.
This applies even when you compare identical tires with different dimensions. It happens because a tire with a smaller profile means the sidewall will flex slightly less. It’s not an overly pronounced difference, but noticeable if you look hard enough.
Proper tire pressure is something that some people tend to ignore, which is why you’ll see many parked cars with flat-looking tires. What if the pressure is optimal, but the tire still looks a bit flat? Is that a problem?
In many cases, it’s not. If you’ve just inflated your tire and it still looks a bit flat, it’s normal, and you should expect to see that. This is by design, and it doesn’t mean your tire is losing air. It’s just as it should be.
With that said, there are a few situations where a flat-looking tire isn’t normal. They aren’t too common, but you should consider them next time you glance at your tires. If your car isn’t too loaded, you haven’t had it parked for too long, and you checked that the pressure is good, then you have nothing to worry about.