Microl Toyota

We will start with a "normal" tire.

A normal tire is worn evenly across the tread surface and the sidewall is free of damage.

Occasionally, we will see linear bulges in a tire's sidewall. It is best to have them checked to make sure they are safe, but most of the time they are associated with the area where the sidewall plys overlap.

This is normal, part of the tire construction. The bulges may be more noticeable on some tires than others.

A rounded bulge in a tire's sidewall is not normal and indicates some sort of damage has occurred. Damage such as this is usually associated with impact damage from a road hazard, such as a pothole or curb. It is common to see damage on the rim edge above the bulge.

Another common sidewall problem is what appears to be scuffing on the sidewall. The lettering or markings on the side of the tire are worn. The most common cause of this is driving on a tire that is drastically under inflated. We don't have to drive very far for this to happen. The tire sidewall will flex as the vehicle moves and weaken the rubber, much in the same way bending a small piece of wire repeatedly will cause it to break. When the tire is removed, the confirmation will be a black, dust like material inside the tire carcass. This is from the rubber that has fallen off the inside due to the flexing.

In these cases, the tire should be replaced.

Another symptom of under inflation is when the tire tread wears on the outside edges of the tire. This happens when the tire is slightly low on pressure and driven for an extended period of time in that condition.

Low tire pressure also creates a drag on the vehicle, slowing it down, reducing handling and performance and lowering gas mileage.

If noticed early enough, the tire can be saved. If not, this tire should be replaced.

While under inflation can cause problems, the same is true for over inflation.

Over inflation will cause the tire tread to wear in the center of the tire, because of the limited contact it makes with the road surface.

Over inflation will cause a "stiff" ride, as the tires are harder than they are supposed to be. They are also more likely to rupture (blow out) if a road hazard (pothole, curb, etc.) is encountered.

If noticed early enough, the tire can be saved. If not, this tire should be replaced.

Tires do go flat for a number of reasons, the most common of which is punctures. It is interesting to note that most punctures occur on the rear tires. Small, sharp objects such as nails, glass or wire are flipped up by the front tire and "caught" by the rear tire.

If the damage is in the tread area it is normally repairable. The repair process should make sure that the hole is sealed all the way through the tire. This will prevent air or water from getting in between the tread ply, which may cause separation of the tread.

Sidewall damage should not be repaired; the tire should be replaced. The sidewall is not as thick or forgiving as the tread.

If a tire puncture is not repaired properly, air or water may be forced up into the hole by normal driving. Over a period of time, the action of the air or water may push the tread plys apart, creating a bubble. As the bubble spreads, the tire will warp and create a noticeable wobbling of the tire. If left unchecked, eventually the tread may separate from the tire carcass, damaging the vehicle or it's occupants.

Make sure any punctures are sealed all the way through the tire and monitor the tire regularly.

Following is an example of tread that has separated from a tire…

It is interesting to note that the tire did not go flat when the tread separated.

Let's move on to more unusual tread wear patterns and information on how wheels are aligned.