Buying Tires

When are tires worn out?

According to most states’ laws, tires are legally worn out when they have worn down to 2/32″ of remaining tread depth. To help warn you that your tires have reached that point, tires sold in North America are required to have molded indicators called “wear bars” across their tread pattern from their outside shoulder to inside shoulder. Wear bars are designed to visually connect the elements of the tire’s tread pattern and warn drivers when their tires no longer meet minimum tread depth requirements.

However, as a tire wears it is important to realize that while its dry traction and handling will improve, its ability to perform in rain and snow will diminish. At 2/32″ of remaining tread depth, resistance to hydroplaning in the rain at highway speeds has been significantly reduced, and traction in heavy snow has been virtually eliminated.

If you plan to drive in wet weather, you should consider replacing your tires when they reach approximately 4/32″ of remaining tread depth. Since water can’t be compressed, you need enough tread depth to allow it to escape through the tire’s grooves. If the water can’t escape fast enough your vehicle’s tires will be forced to hydroplane (actually float) on top of the water, losing traction.

How many tires should I buy?

Just one tire?

If your tires have a lot of remaining tread depth, but you need to replace just one damaged by an accident, road hazard or a vandal, you should replace it with a tire that matches the others exactly. That means getting a replacement tire of the same brand, model, size and speed rating. Tires that are not the same will not handle the same. You may not notice the difference during casual driving, but during emergency braking or evasive maneuvering the car may not handle the way you want it to. Some cars like Subarus and Honda CRV 4wd have very specific requirements for matching tread depth on all four tires.

A pair of tires?

If two of your tires have a lot of remaining tread depth, but you need to replace the other two because they were damaged or worn out, you should replace them with a pair of tires that come as close as possible to matching your existing tires. While identical new tires are desirable, others of the same size and type can also provide good results. Only consider selecting new tires that are from the same tire category as your existing tires.

A set of tires?

If all of your tires are wearing out together, you have the greatest flexibility in tire selection. If you were happy with the original tires, simply replace them. If you want longer treadwear, a smoother ride or more handling, there are probably tires that will help you accomplish that. Review the tire category types until you find a category description that describes a tire that fits your needs.

How long do tires last?

How long tires last depends on four things: the design of the tires, the pavement condition of the roads you drive on, how you drive, and how well you maintain the tires. You have no control over tire design, other than trying to choose a long lived tire based on treadwear ratings and mileage warranties. You don’t have control over the pavement conditions either. However, you do have control of how you drive. The harder you accelerate, brake, and corner, the quicker the tires will wear. You also control maintenance. Maintenance of tires includes rotation and balance every 5,000 miles to 7,500 miles, maintaining proper tire pressure, and keeping the tires aligned. The better you maintain the tires the longer they last. Depending on the combination of the above factors, tires can last between 5,000 miles and 70,000 miles.

What’s the proper inflation pressure for my tires?

This is not an easy question to answer. Everyone has different opinion. I think most experts will agree on the following though.

  • Tires shouldnever be run under-inflated. That is, under the PSI recommended in your owner’smanual.
  • Tires shouldnever be run over-inflated. That is, over the maximum pressure on the tiresidewall.
  • If a tireis wearing on both outer edges it is under-inflated.
  • If a tireis wearing in the center it is over-inflated.

Here’s our opinion on how to get the proper pressure for your tires. We feel that the owner’s manual recommendation is often too low. Why? Because we have see customers wear the inner and outer edges of a tire with documented history of manufacturers recommended inflation pressure. We use the following controversial method: fill the tire to an amount under the max PSI listed on the sidewall. For 32 PSI max tires we recommend filling to 30 psi when cold. For 35 max PSI tires we recommend filling to 32 PSI. For 44 PSI max tires we recommend filling to 36-38 PSI cold. Are these the exact perfect tire pressures for your car? No. Many cars using the exact same tires weigh different amounts and therefore require different pressures. You can fine tune the pressure for the best tire wear. If you disagree with our method, feel free to use someone else’s or make up your own. Just remember never to inflate under the owner’s manual pressure recommendation. If in doubt, it’s usually better use a higher pressure.

Why are tires so expensive?

Tires are not very expensive when compared with other automotive maintenance costs on a per mile basis. Gas seems fairly cheap if you consider its price one tank at a time. However, if you keep track of your costs per mile, you’ll find that typical total fuel costs for just 10 to 20 thousand miles of driving actually exceed tire costs. When you are selecting new tires, consider evaluating your situation by comparing “how much per mile” each tire will cost. Divide the number of miles the tire is likely to last (you can use the warranty mileage for an optimistic number) by the cost of the tires you are considering. Frequently you will find that tires that are initially inexpensive end up costing more per mile. Not to mention the fact that cheap tires are more likely to develop defects before the tread has worn down.

Aren’t tires much cheaper at Costco?

Costco is a great place to buy wholesale items. In other words items you might buy to sell to other people – huge tubs of nacho cheese sauce, enormous boxes of candy bars, etc. Tires at Costco are not wholesale items. They install tires for you, the retail customer, at retail prices. No one who sells tires buys them at Costco because the prices are too high for them to be resold at a profit. Having said that, there may be some savings to be had since Costco does buy a lot of tires they probably get a very good price and could pass that savings on to you. However, it’s impossible to know for sure. See the next question to find out why.

But I checked and a Michelin is cheaper at Costco!

Check the model number carefully and you will notice that it is not exactly the same as the “real” Michelin model number available at regular tire stores. Costco buys a huge number of tires and the tire manufacturers make a house brand just for them. Are the tires exactly the same other than one extra digit in the part number? I don’t truly know. But if they are the same, why add the extra digit? I remember reading an article on how to choose a mattress a while back, and one of the points it made was that upon disassembling name brand mattresses made for department stores they found the construction differed from the regular version of the mattresses and therefore pricing of the two could not be fairly compared. Of course these are tires not mattresses, and Costco not Montgomery Wards, so if anyone wants to do some relevant research I’d be thrilled to hear your results.

How do I choose a tire?

This answer will focus on how to purchase a passenger car tire since that is all we sell at Art’s. If you want a non-stock performance tire or large truck tire then you should go to a shop with a working knowledge of these types of tires.

The quickest way to compare the life expectancy of tires is to use the mileage warranty as a guide. You should not expect the tires to actually last the length of the warranty though, unless you do mostly freeway driving, and are very freakishly careful about tire pressure, alignment, and rotation. Some manufacturers are also banking on the fact that most people will not attempt to apply for warranty credit if their tires wear out before the warranty period has expired, and give extremely unrealistic treadwear warranties. You can also look the the treadwear component of the UTQG rating. However, each tire manufacturer does their own testing, so the numbers will not always be a realistic measure for cross brand comparison. For instance Bridgestone tires are usually very modest in their UTQG treadwear numbers, whereas Michelin numbers usually seem overstated.

Make sure to consider the load rating of the tire. Choosing a tire without an adequate load rating will lead to premature wear, and possibly tire failure. Choosing a tire with a higher load rating may yield better fuel economy as well, although this gain may be made at the expense of ride comfort.

Choosing a tire that meets the manufacturers’ speed rating is advisable, but not critical in my opinion. If you have a speedy car, but drive like a grandma, I don’t see why you need to have a tire with a high speed rating. On the other hand, if you have slow Civic, and drive like a maniac, you should probably invest in a tire with a higher speed rating.

Tire models change every 3 to 5 years, so by the time your car needs its next set of tires, the model you were so happy with last time may be discontinued, and the replacement may not be as good. If you don’t know about brands and models from personal experience or research, it’s probably better to let someone with experience with the particular tire line recommend a tire for you. Be sure to explain what you are looking for in a tire to your adviser. Tires come in all styles, just like shoes. It’s entirely possible to recommend an excellent work boot to someone who is really looking for a running shoe.

If you have the energy to learn about and then compare the UTQGS ratings here’s some information I pinched from the Web.

Uniform Tire Quality Grading System

The Uniform Tire Quality Grading System (UTQGS) is a tire information system designed to help buyers make relative comparisons among tires. The UTQGS is not a safety rating and not a guarantee that a tire will last for a prescribed number of miles or perform in a certain way. It simply gives tire buyers additional information to combine with other considerations, such as price, brand loyalty and dealer recommendations. Under UTQGS, tires are graded by the manufacturers in three area: treadwear, traction and temperature resistance.

The UTQGS information is right where you need it — on the tires. The grades can be found on two places on the tire:

  • there isa paper label affixed to the tread, and
  • the gradesare also molded into the sidewalls.


The treadwear grade is a comparative rating based on the wear rate of the tire when tested under carefully controlled conditions. For example, a tire graded 200 should have its useful tread last twice as long as a tire graded 100. However, real world tire tread life, in miles, depends on the actual conditions of their use. Tire life is affected by variations in driving habits, service practices — such as tire rotation, wheel alignment, maintaining proper inflation pressure, differences in road characteristics, and climate.


Traction grades represent the tire’s ability to stop on wet pavement as measured under controlled conditions on asphalt and concrete test surfaces. The traction grades from highest to lowest, are “AA”, “A”, “B” and “C”. A tire graded “AA” may have relatively better traction performance than a tire graded “A”, “B” or “C”, based on straight ahead braking tests. The grades do not reflect the cornering or turning traction performance of the tires.

Temperature Resistance

Temperature grades represent the tire’s resistance to heat and its ability to dissipate heat when tested under controlled laboratory test conditions. Sustained high temperature can cause the tire to degenerate and reduce tire life, and excessive temperature can lead to sudden tire failure. The temperature grades from highest to lowest are “A”, “B” and “C”. The grade “C” corresponds to the minimum performance required by federal safety standard. Grades “B” and “A” represent higher levels of performance than the minimum required by law. The temperature grade is for a tire that is inflated properly and not overloaded. Excessive speed, underinflation or excessive loading, either separately on in combination, can cause heat buildup and possible tire failure.

What kind of tires do you sell?

We sell Toyo tires. When we were first considering selling tires, we knew that we would need to concentrate our tire business with one supplier in order to get a good discount rate. Buying in bulk saves money. If we were to split our tire purchases between many vendors, we would end up paying more for tires and therefore we would need to charge more for tires. If you’ve ever had to buy an emergency replacement tire at a gas station, you know what I’m talking about. Knowing we needed to pick one manufacturer, we then needed to decide which tire manufacturer’s line would match our customers’ needs. We think most of our customers are looking for value in the true sense of the word – high quality for low prices. This is why we chose Toyo. They don’t spend a lot of money on ad campaigns, but they do spend a lot of money on research and development and quality control. Even though you may not have heard of Toyo, they are far from a small company. In fact they are among the top 10 producers of tires in the entire world.

What tire sizes do you have?

We carry most stock passenger car tires for the cars we repair. We do not stock most of the light truck and high performance sizes. Tires are the highest cost yet lowest profit part we sell. Some sets of tires are over $600 wholesale. Our current stock is worth just under $10,000. We simply can’t afford to stock the larger and more expensive sizes. In addition to the cost, tire aging is another reason not to stock the slower moving sizes. The rubber in tires deteriorates over time, even if they are not being used. We would be doing our customers a disservice by selling tire that had been sitting on our rack for years. This does not mean that we can not get whatever size you need. Tires ordered before 5:00 will arrive the following day at 3:30.

What kind of warranty do your tires have?

Tire warranties are a pain. The tire manufacturers want to prevent installers from giving warranties where they are not due. For instance, a tire manufacturer would not want to warranty a tire prematurely worn due to misalignment, or a ply-separation caused by a collision. In their effort to prevent installers from wrongly warranting tires (and, I think, a real desire to do failure analysis), they make it very difficult to make valid warranty claims as well.

The process goes like this: the tire is removed from your car and marked as a warranty and sent to our distributor who then sends it to the manufacturer. The manufacturer then examines the tire to determine the cause of the failure and decides whether it deserves warranty credit. If so, they issue a credit to our distributor who issues a credit to us. We are told this takes 3 to 6 months. You didn’t have to use your car for anything did you? Just kidding. While the fate of the warranty is being decided a new tire of the same make and model is installed on your car that you have to pay for. In the event that a warranty credit is issued, you get a refund of the portion of the warranty left on the tire (they’re prorated warranties).

This warranty doesn’t fit very well with the “Art’s” way of doing business. If you want to go through the warranty process in the above described manner, then you are welcome to. If not, then we have a easier to deal with “good will warranty”. If a tire that was well maintained fails from a manufacturers defect with at least 4/32″ left on the tread, then we will sell you another tire at the wholesale price.

Installation of the tire is free for one year after purchase and the normal price thereafter.

Your warranty sucks! Big O changed my tire when I hit a curb and it didn’t cost me a cent.

Big O and other tire dealers often offer a “road hazard” warranty that includes replacement of tires while the tread is in good condition for any type of damage or defect, sometimes with no pro-ration. This type of warranty is not really a warranty but more like insurance. You pay extra, usually a percentage of the price of the tires, for the road hazard warranty when you buy the tires.

Like insurance and gambling, the house always wins. You may get lucky and come out the winner with a blown tire, but more likely you will not get to use the warranty, either because the tires don’t have a problem, or when they do have a problem you aren’t close enough to Big O to make it cost effective to tow your car there instead of a closer tire shop. However, if you know you are an …. um, unlucky driver then it might make sense to get this type of warranty.