How To Read Tire Wear
Below are some of the most common types of tire wear we encounter, along with likely causes for each. Keep in mind that each type of wear may result from several possible factors, so use this as a helpful guide rather than a definitive diagnosis.
Hot Tear
A hot tear is caused by the tire being underinflated, causing the tire to generate too much heat which results in the tire melting apart. The wear pattern is similar to water beading off the window of your car.
Cold Tear
A cold tear is caused by the tire being overinflated, making it hard to get even heat in the tire. When this happens, the surface of the tire in direct contact with the ground generates heat very quickly while the rest of the tire is cold. When the carcass of the tire isn’t up to temp, the tire will literally tear itself apart.
How to tell a hot tear from a cold tear? The simplest way to tell them apart is if you can put your fingernail underneath the ripped-up rubber, it’s a cold tear. If you cannot put your fingernail underneath the rubber, it’s a hot tear. If you’re not sure, think about your tire pressures. If your optimal range is 30-32psi and you’re set to 35 psi, it’s a safe bet that it’s a cold tear. The opposite of this is true with an under inflated tire.
Coasting
Small patches of tire with a different tread wear next to the siping in the tire are the easiest way to tell that the rider is coasting - usually on corner entry, or waiting too long between transitioning from brakes to throttle after the apex of the corner. Don’t confuse these patches with rebound issues.
Throttle Line
You can tell a lot about how someone is riding by where they’re picking up the throttle. Are they all the way on the edge of the tire when they start to slowly crack the throttle open or are they waiting until the bike is almost straight up and down before they apply the throttle? Are they gently rolling into the throttle or are they smacking it hard and causing the tire to develop a shoulder.
Rebound
When you look at the tread, the easiest way to tell the rebound is out of adjustment is the siping (that’s the cutouts in the tread to displace water) in the tire. If you’re on slicks, look for the wear markers. If the rubber is wearing down excessively on one side, and rolling the tread on the other, it’s a sign that the rebound is either too fast or too slow. The easiest way I have found to tell the two apart is if the tread is cutting in the front, the rebound is too fast, and if the tread is cutting in the rear, the rebound is too slow.
If you are running slicks, these will look more like a comet tail. Same as before, if the “tail” is on the front of the tread depth hole, the rebound is too fast, and if the tail is behind the hole, rebound is too slow.
Compression
Compression is harder to tell by the looks, but occasionally you will see a wavy patterns on the side of the tire, similar to the zig-zag from a rebound adjustment, though generally not nearly to the same extreme. Be sure to set the compression off the needs of the rider, not necessarily solely off the tire wear. See the article “Suspension 101” for more information.
Compound Lines
When you see a nearly perfectly straight line in the middle of the tire, this is a result of a dual compound tire. The edge of the tire is made with a softer compound allowing for more grip while the harder center compound provides more life out of the tire.
Compounds
Choosing the right compound is crucial to getting the most life out of your tires. Different compounds are designed to operate within certain operating temperatures, If its 105 degrees outside and you’re racing on a tire that’s designed to be used in 65 degree weather, you’re not going to get much life out of that tire. You actually run the risk of overheating that tire, which not only compromises tire life, it also compromises the amount of grip you have. The tire will begin to feel slick or greasy. Each tire manufacturer has a chart for their recommended tire compounds and pressures for a given temperature.
Blue coloration
If you’re new to track, or just new to pushing your tires, you may be surprised to see the tires turn blue, but this is completely normal.
This is the result of a chemical reaction where the tires are getting hot enough to release oils and other chemicals. As the oils oxidize on the surface of the tire, the tire turns blue. This is perfectly fine and you can continue to ride on the tire without worry, though after enough heat cycles you may notice the grip of the tire decreasing. This is more noticeable in racing slicks than regular street tires due to how the tires are designed.
Ideal Tire Wear
Perfect tire wear should look like a beach after the tide has gone out. There should be no harsh lines or creases, no hot/cold tears, no hard shoulder from being rough on the throttle. No curling the tread, or comet tails, from rebound adjustment.
The perfect tire wear does exist, however it’s important we remember that the bike needs to be set up to how it rides, not just what the tires look like. Just because the tire looks great doesn’t mean the bike is set up to give you your best lap.
