Cracked Tire: Tolerance And When To Replace

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If you find a crack in a tire, you may be concerned, “Is it safe to drive on this ……? However, replacing tire costs a certain amount of money, so if there is no problem, you want to use the tire to the end of its life.

It is common knowledge that if you see a slip sign, you should replace the tire, but the question arises, “How much can I tolerate regarding cracks?” However, the question arises, “To what extent is it acceptable to replace a tire with a crack?

And, “Will a cracked tire pass vehicle inspections? There may also be concerns about whether a cracked tire will pass vehicle inspections. In this issue, we will explain the “acceptable range of cracks in tires and when to replace them.

How Much Cracking Of Tires Is Acceptable?

If you continue to drive with a cracked tire, the rubber will eventually burst (rupture). Because of the danger of a serious accident, it is highly recommended to know the acceptable range of cracks in a tire.

Five Levels Of Tire Cracks

Tire cracks can be divided into 5 levels (3 major levels) as follows

  • Levels 1 and 2: Continued use is possible.
  • Levels 3 and 4: Usable (caution required)
  • Level 5: Dangerous

If the surface of the tire shows faint cracks or wrinkles, it is classified as Level 1 or 2 and there is no problem with continued use.

If the cracks on the surface of the tire are clearly visible and the depth of the cracks is about 1 mm, the tire can be considered Level 3 or 4.

However, it is a sign that the tire is approaching its limit, so it is necessary to monitor the tire on a daily basis to see if the cracks are getting deeper. If the cracks reach deep into the tire, they are at level 5, which is dangerous.

If the crack has reached the carcass inside the tire, it is one step away from bursting, and the tire should be replaced as soon as possible.

What Is The Maximum Level That Will Pass Vehicle Inspection?

In actual driving, tires up to level 3 or 4 can be used. But what are the standards for passing vehicle inspections? In fact, there is no clear regulation regarding cracks in tires, although there is a regulation regarding tire grooves of 1.6 mm or more for tires related to vehicle inspections.

Therefore, the decision to pass or fail a vehicle inspection is left to the judgment of the inspector at the time. Although it cannot be said with absolute certainty, if the cracks in the tire are limited to the surface, it is highly likely that the tire is safe.

If it is more like a crack than a crack, as in the Level 5 condition, it will fail. Even if the vehicle passes inspection, a cracked tire is still unsafe, so daily inspection and replacement of the tire as soon as possible are advisable.

Be Careful Driving On The Highway!

As speed increases, the air pressure rises as the inside of the tire warms up, and the unevenness of the road surface causes more shock than at low speeds.

In other words, the conditions are harsher than usual for tires. For these reasons, driving on the highway with cracked tires increases the risk of bursting.

Stopping on the highway is very dangerous, and bursting at high speeds can easily lead to accidents, such as spinning out of control. If your tires have cracks above level 3 or 4, be careful driving on the highway.

If Used Beyond Acceptable Limits…

Similar to the highway example above, continued use of a tire beyond the acceptable range of cracks can lead to a tire burst, even in the speed range of a regular road.

Not only is this simply dangerous, but if the wheel is deformed by hitting the road surface during a burst, the repair cost will be more expensive than a tire replacement alone.

Considering the danger and the possibility of incurring extra repair costs, it is wise to replace the tire immediately at around level 3 or 4.

Causes Of Cracked Tires

So far, we have explained what happens when a tire cracks, but what causes a tire to crack in the first place? You might think, “Isn’t it simply age-related deterioration?” You may think, “Isn’t it simply due to aging?

Age-Related Deterioration

Regardless of how often a car is driven, all parts deteriorate over time. And among the parts that deteriorate, rubber is the most obvious. Tires are exposed to direct sunlight, rain, snow, and constant force from uneven road surfaces and loads while driving.

Tires deteriorate particularly quickly over time. Tires contain a lot of oil, but as they deteriorate, the oil is drained out and the rubber dries up. As they dry out, the rubber loses its elasticity and begins to crack on the surface.

Insufficient Air Pressure

When tires are underinflated, they become deformed and do not maintain their correct shape. Driving with deformed tires puts a strain on the tires and can cause them to crack.

In addition to causing cracks, under-inflation can also cause the following symptoms

  • Decreased grip (poor driving performance)
  • Increased susceptibility to uneven wear
  • Fuel consumption will worsen.
  • Heat separation (damage due to abnormal heat generation)

Excessive Load

Tires always support the weight of the vehicle. If the weight is increased by carrying extra luggage, etc., the tires are further overloaded, which can accelerate tire cracking.

Infrequent Driving And Long Periods Of Inactivity

Tires contain an “anti-degrading agent” that is designed to gradually seep out of the tire through centrifugal force while the vehicle is in motion.

If the car is left off the road for a long period of time, this anti-degradation agent does not seep into the tire properly, causing the tire to deteriorate prematurely and crack.

Also, if the car is parked for a long time, only a portion of the tire is pressed against the road surface, causing it to deform and crack. Moving the car occasionally will help extend the life of the tires.

Oil-Based Tire Wax

Tire wax can blacken the sidewalls of tires and make them look tighter. This can be water-based or oil-based, but oil-based tire wax actually has the side effect of damaging the rubber in the tire and accelerating deterioration. If you want to apply tire wax, use the water-based type.

Ultraviolet Rays

Ultraviolet rays are notorious for deteriorating rubber and plastics. Of course, tires are no exception, and ultraviolet rays will accelerate deterioration.

Although exposure to ultraviolet rays is unavoidable when the car is in motion, it is possible to deal with this problem by covering the car when it is parked in a parking lot, or by shading it from the sun with a carport, etc.

How To Prevent Tire Cracks

We have discussed earlier the causes of cracked tires, but what should you do to prevent cracks?
Let’s find out how to do that below.

Make The Car As Light As Possible

As explained earlier, carrying extra luggage in the car increases the weight and the load on the tires.

Also, unnecessary luggage in the car will have a negative impact on fuel efficiency in addition to tires. Unload unnecessary luggage and try to avoid unnecessary load on the car.

Check Air Pressure Frequently

Insufficient air pressure can cause tire deformation, leading to poor fuel economy and cracks. It can also lead to reduced grip performance, such as increased braking distance.

It can also cause damage such as uneven wear and heat separation. Since the condition of tires can be life-threatening, make it a habit to check the air pressure on a regular basis.

It is recommended to check the air pressure gauge at the gas station every time you fill up your gas tank.

Do Not Over Wash Tires

Tires contain oil, and washing tires too much with detergent or other detergents can cause them to lose oil and deteriorate. However, not washing tires at all is also not a good idea because of the accumulation of dirt.

If tires are not washed frequently, it is unlikely to become a major problem, so moderate washing is fine. When washing, be sure to gently rinse the tires with water (no detergent).

Avoid Exposure To Acid Rain

In addition to ultraviolet rays, acid rain can also cause deterioration of tire rubber. Acid rain is harmful to humans, but it also oxidizes and deteriorates tire rubber.

When parking a car, it is advisable to park it in a covered area or cover the car as much as possible. This will kill two birds with one stone by preventing deterioration not only from acid rain but also from ultraviolet rays.

Prevent Tire Problems Other Than Cracks

It is no exaggeration to say that tires are the most important component of a car. Preventing all kinds of problems, not just cracks, is the key to safety. Below are other tire problems besides cracks and how to prevent them.

Check For Uneven Wear As Well As Cracks

When inspecting for cracks, it is also important to check for uneven wear. Uneven wear is a phenomenon in which the tread surface (the surface in contact with the ground) of the tire does not wear evenly, but wears unevenly.

There are three types of uneven wear:

  • Single-sided wear
  • Double-sided sliding wear
  • Center wear

One-sided wear is often seen on heavy vehicles (minivans, etc.) and is caused by a strong load being placed on the outside of the tire when making a curve. One-slip wear is also more likely to occur when the car is lowered.

Double-shoulder sliding wear is caused by under-inflation, while center wear occurs when the air pressure is too high. Both too high and too low air pressure can cause uneven wear.

Regardless of the pattern, uneven wear not only increases vibration and road noise but also reduces the grip of the tire. Only one-sided wear may be temporarily resolved by rotating the tires, but the only way to remedy uneven wear on both shoulders and in the center is to replace the tires.

Check For Pinch Cuts

Pinch cuts are deformed areas of the sidewall of a tire that is popped up and deformed. Pinch cuts are caused when the carcass cords (the tire’s internal framework) break.

When the carcass cords break, the broken portion is supported only by rubber, which expands outward due to air pressure, causing the tire to bulge outward and become pinched.

The most common cause of a broken carcass cord is a tear caused by the impact of a vigorous ride up a curb. Another possible cause is when a crack in the tire reaches the carcass (Level 5).

Naturally, a tire in a pinch-cut condition is very weak, and if the rubber cannot withstand the pressure, it will burst. Unfortunately, the repair is not possible, so if you find a pinch cut, replace the tire as soon as possible.

Check For Foreign Objects Stuck In The Tire

When inspecting for cracks, it is also important to check for nails or pieces of steel stuck in the tire. If a foreign object is stuck in the tire, there are two types of air leakage.

  • In the case of a foreign object stuck in the tire, there are two types of air leaks.
  • A puncture occurs when the tire loses air quickly.

If the tire is already flat, it is impossible to drive on your own. However, if the air is gradually leaking out, you may be able to drive on your own to a nearby gas station or another store that can repair a flat tire.

You may be tempted to immediately pull out the foreign object stuck in the tire, but if you think you can drive on your own, never do so.

This is because the tire will go flat the moment the foreign object is removed because there will be nothing to plug the hole. Tread surface punctures can be repaired and can be taken to a store to be fixed.

In addition, self-repair kits are available, so those who are good at DIY can also self-repair. However, please note that depending on the size and shape of the hole, it may not be repairable.

When Is The Approximate Time To Replace Tires?

To avoid cracks in tires, it is essential to replace tires at the appropriate time. The timing of tire replacement depends on the mileage, elapsed time, and usage conditions, but here are some examples of generally accepted replacement times.

Mileage And Elapsed Time

The first and most obvious indicator is the mileage. It depends on the type of car and the brand of tire, so it can be used as a rough guide, but it is generally said that tires wear out by 1 mm after 5,000 km.

A new tire has approximately 8mm of grooves, and there is approximately 6.4mm of the room until the slip sign of 1.6mm. Therefore, we can say that it is time to replace tires when they reach 6.4 x 5,000 = 32,000 km.

In terms of elapsed time, it is recommended to replace tires after 4 to 5 years. As for studless tires, it is advisable to replace them after 3 years or so, since the rubber is soft and easily deteriorates.

To determine the year of manufacture, look at the stamp on the sidewall of the tire; tires manufactured after 2000 have a four-digit number, such as “3119.

The first two digits indicate the week of the year (31st week), and the second two digits indicate the year (2019). So, in this example, we know that the tire was manufactured in the 31st week of 2019 (around August).

What Is The Approximate Time To Replace A Tire If It Is Cracked?

As explained at the beginning of this article, there are five levels of cracks in a tire. 1 and 2 are acceptable for continued use, but at 3 and 4, it is time to replace the tire.

Cracks at levels 3 and 4 often occur after 3 to 4 years, so it is advisable to replace them after 4 to 5 years at most. If you are unsure of the degree of cracking, we recommend that you consult your dealer, car accessory store, or gas station.

What Is The Approximate Timing Of Replacement When The Remaining Grooves Are Low?

Tires have a slip sign to check the remaining grooves. The slip sign is a raised area at the bottom of the tire grooves on the tread surface. If the slip sign appears on the tire surface, the tire will fail inspection.

The slip sign is an extension of the △ mark on the sidewall of the tire and should be used as a guide when checking.

Note that although a tire will pass inspection if the slip sign is not fully visible, performance will be extremely degraded if the remaining grooves are less than 3.2 mm (1.6 mm from the slip sign).

In particular, when it rains, hydroplaning (a phenomenon in which the vehicle slides on water and cannot be steered or braked) can easily occur, making it extremely dangerous.

Where Is The Best Place To Change Tires?

We have discussed the acceptable range of cracks in tires and when to replace them. If you need to replace your tires, where should you go to get them done?

The following is a summary of the characteristics of car accessory stores, gas stations, dealers, and other companies that provide tire replacement services.

Dealers

Many dealers that sell new cars also offer tire changes. Dealers may have an image of something expensive. It is true that both labor and tire prices are higher than those of other companies.

However, there are cases where you can get a discount by taking advantage of campaigns. The advantage of a dealer is a sense of security.

Even if you are not sure about tire selection, they can help you choose the right tires with accurate advice. You can be sure of the level of work performed, and there are also benefits such as a maintenance warranty.

Gas Stations

Many gas stations actively accept tire changes, as evidenced by a large number of tires available when you visit a gas station. Those who have a gas station in their neighborhood will benefit from the convenience.

Another advantage is that they are likely to be able to change tires on short notice. However, the disadvantages are higher prices and a lower level of work if the store does not perform the work frequently.

If a store is actively promoting tire replacement (and you often see them working on tires), you can rest assured that the work will be done to a high standard.

Car Accessory Stores

Many people probably think of car accessory stores when they think of changing tires. The advantage of car accessory stores is that the labor cost for changing tires is low, but the disadvantage is that the level of work varies. Nevertheless, it is not a bad choice for those for whom cost is important.

Online Shopping & Bringing Your Own Tires

In terms of low cost, nothing beats this combination. The advantage of online shopping is the low price of the tire itself. However, when you purchase tires by mail order, you have to ask some stores to change tires for you.

Some stores charge a higher labor fee if you bring your tires in, so you will want to choose your store carefully. In recent years, however, an increasing number of stores have begun to welcome customers who bring their own tires.

Since such stores charge less for labor, you can save money on both the cost of tires and labor. In addition, such stores are often able to deliver tires directly to the store, eliminating the need to carry tires from home to the store.

The level of work itself is also of a high standard, as they specialize in this type of work, and there are no disadvantages other than the fact that you have to choose the tires yourself.

Conclusion

How was your experience? Tires are a very important part of a car’s safety. Cracks in tires may cause concern, but if they are only level 1 or 2 (slight cracks on the surface), they do not affect driving.

However, as the progress of the crack, the danger of bursts and other problems increases, so it is essential to observe the cracks on a daily basis. When doing so, it is also important to look for other problems such as pinch cuts or foreign objects sticking in.

It is also important to try to reduce the load on the tires as much as possible by checking air pressure and unloading unnecessary loads. If you need to have your tires changed, refer to the “Where to Get Your Tires Changed?” section to find the right store for you.