Last time we talked about tire pressure and how it can effect your vehicle: altitude, temperature, age. But, how does your vehicle effect your tires? It turns out the relationship between tire and vehicle are symbiotic. True, tires won’t tell you your engine is out of oil, and they can’t tell you why your stereo isn’t working, but they can tell us if the alignment is off and if there is something wrong with the suspension or frame.
There are several types of wear to keep in mind when looking at your tires.
- An Even Wear is ideal. No part of the tread is wearing faster than any other part of the tread. The rubber is free of cracks and other oddities, which may include bulbous tumors in the side of the tire — commonly called the sidewall. Even so, there are problems that may occur in the tire that you are unable to see on the surface, but you will feel when driving. A gradual Tire Pull can be a symptom of a bad tire. A quick lesson on how tires are made. The tread of the tire is where the bulk of the rubber gets the most abuse. Beneath that thick layer of rubber there are other layers. Some of those layers have steal cords that overlap to create a flat braid or sorts. If the curing process is not perfect, those cords can slip allowing air to seep in and create a bubble over time. I’m sorry to say, but it happens ALL THE TIME. Tires are not perfect. As humans our technique is very good, but when a company ships out millions of tires a month a portion is going to be defective in some way, and in most cases the issue is resolved. The problem is spotted. The tire is replaced. The customer has a perfect day from there on out. Can brand new tires have issues? Yes, they can. A lot of defects slip a visual inspection. Should you worry? No. If you don’t feel any abnormalities while driving there isn’t need for concern.
- Over-Inflation and Under-Inflation of a tire is one of the easiest issues to spot. If the tire is Over-Inflated the tire will ride on the center of the tread, wearing it thin. If the tire is Under-Inflated the tire will wear on the inner and outer edges of the tread. Fixing the issue is easy. Check your tire pressure at each tire to make sure they have the same PSI . Most domestic cars will require 40-45 PSI, while trucks can take as much as 80 PSI. When in question be sure to check the sidewall for the correct amount.
- Inner or Outer tire wear — this is where it gets a little complicated. This wear pattern looks similar to the inflation issues I mentioned above. The only difference is that Inner and Outer tire wear is usually only present on one side of the tire. Both front tires will also wear opposite of each other. Here’s another good way to look at it: if you stand up and point your feet straight forward that is how your tires are suppose to roll down the road. Now point your toes together. This is what your tires look like when they are Toed In, which would also mean they will probably wear the outside of each tire because that is the edge with the most force applied when the car is moving. Now point your toes out. Can you guess which edge this will wear? If you said the inside, you get a gold star. But, what does this type of tire wear mean? It can be alignment issues or it can be worn parts. 9 times out of 10 it will be the alignment. Once in a while it will be tie rod ends that need to be replaced. You can check the tie rod ends on your own, but this will require crawling around on your back, and perhaps even a jack to lift the tire off the ground. Since this is about keeping our hands as clean as possible, it’s usually best to have a mechanic check it out. I would also recommend having different shops do an estimate so you can see if anyone is trying to throw you a curve ball and replace parts that aren’t needed. If you are strapped for time and don’t want to spend all day getting estimates, ask the mechanic if they can show you the worn parts while the vehicle is on the lift. If they tell you no, I would go somewhere else.
- Inner and Outer tire wear can also mean something else, what mechanics call Camber issues. Let’s get back on our feet and keep those toes straight. Move your feet shoulder length apart. Good. Now, without moving your feet, bring your knees in until they touch. Do you see the angle yours calves make? This is called Negative Camber. If you were to spread your knees and stand bow-legged this would be called Positive Camber. Similar to Toe, Camber can wear on the inside if it’s Negative, or on the outside if it’s Positive. Again, similar to Toe this issue can result from alignment issues or worn parts. In some cases, aftermarket parts are needed to add additional adjustment to the alignment settings. I wish I could go through every car out there, and realistically I wouldn’t have to because a lot of suspensions are almost identical to one another. The problem is diagnosis. Even a trained, educated, and experienced mechanic can misdiagnose a vehicle. It’s nothing personal. There are a number of moving parts connected through your steering wheel: Rack and Pinion, Inner and Outer Tie Rod Ends, Steering Knuckles, Ball Joints, Control Arms, Sway Bar, Wheel Bearings/Hub Assembly, Struts/Shocks, and that’s for most of the domestic cars out there. Once you get into trucks and four-wheel drive vehicles there are even more parts on top of what I’ve already mentioned: Drag Links, Idler Arm, Pitman Arm, Gear Box, Track Bar, Steering Shock. It’s not always an easy or inexpensive fix. On a daily basis if I were to replace all four Ball Joints, plus alignment afterward, I come out to about 800-900 dollars. That’s including parts and labor. Dodge trucks I have to charge more on labor because they take longer to remove. Prices on parts are getting more expensive all the time. A semi-new truck, one that is fresh out of warranty with the dealer, will have to get their parts from the dealer for the next year or two, or at least until the parts are picked up by other manufactures and distributed to your local part stores. One Tie Rod End for a newer Ford can cost as much as 150-200 dollars, depending on how it is marked up. If it comes from the dealer, it could cost even more. (Rambler.)
- This last group of tire wear is odd and can vary depending on the issue. Flat Spots and patchy wear can indicate your tires need to be balanced, rotated, and perhaps replaced if the damage is too great. Cupping and Feathered Tread can point to bent control arms, bent strut/shock, or even frame issues. If you suspect frame damage a quick way to get an over view is to flatten your hand stick your fingers between your tire and the body. Do this for both the front and back of the front tire, then go to the other side of the vehicle and do the same thing. If the space is equal to each other it’s safe assume your frame is straight. If for instance you can fit three fingers on one side and four on the other side, it could mean one of the tires is shoved back. Back to using our toes for a metal picture, stand with your feet shoulder length apart and even with each other. Now, take your left foot and scoot it backward a couple inches. It doesn’t look like it would be much of an issue, but it is. When the tires aren’t even with one another, it may produce shaking in the steering wheel and the floor. It could’ve happened when you turned too sharp into the parking lot and hit the curb, or maybe the roads were icy. Either way its a problem and it will eat tires as if they were candy. This kind of situation will also start wearing other parts on the vehicle if it’s not addressed.
A combination of any of the above will do bad things to your day, and you should get it checked out at your earliest possible convenience. It’s kind a lot to keep in mind when looking at a tire, but it’s good knowledge to have. Without getting into future subjects like alignment and brakes, there are a few other things to mention to your mechanic before they check out your vehicle. Shaking and Pulling are two symptoms that can help someone diagnose what’s wrong. Whereas Pulling happens in the steering wheel and usually indicates an Alignment Issue or a Tire Pull, Shaking can occur in several place. If you feel Shaking in the steering wheel it can indicate a need for tire balance, alignment, or worn parts in the suspension. If you feel Shaking in the brake pedal it can indicate brake service and possibly rotor replacement. If you feel Shaking in the seat or floor it can indicate an issue elsewhere in the car.
Anyway, I’ve rambled long enough about tires. So, until next time, keep those hands clean.
If you have any questions, or topic suggestions, please feel free to email me or leave a comment.