When To Replace Tires: 3 Things You Should Know

When to replace tires

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You should know when it’s time to replace those tires. But how long to do tires last anyway? What’s treadwear rating & when is the best time to buy tires? We break it all down so you can grab a new set of rubber with confidence. 

by Kelly Taylor

1. How long do tires last?

Hold out your hands and say “This long.”

Sound a little arbitrary? That’s because no two tires — even the same brand and model — will last the same for everyone, and the lifespan of a tire depends on factors such as temperature, speed, quality of roadways, the alignment of your vehicle and how well they’re maintained. That includes how much attention you pay to proper inflation. 

Summer vs All-Season Tires

For example, one tire, a high-performance summer tire, is warranted for six years or 50,000 kilometres. From the same brand, a passenger all-season tire is warranted for six years or 104,000 kilometres. 

Those treadwear warranties are primarily marketing, not science, as the tiremaker isn’t actually guaranteeing a tire will last that long, merely that the tire will be replaced subject to certain conditions if that lifespan isn’t met.

Unmounted tires should not be hung, as the sidewall can be irreparably distorted. Tires not mounted are best stored upright; a wall rack is handy.

Even the Rubber Manufacturers Association is loath to put hard numbers on the lifespan of tires. “The RMA is not aware of scientific or technical data that establishes or identifies a specific minimum or maximum service life for passenger and light truck tires,” the association says in a pamphlet.

Complex Tire Makeup

A tire is far more complex than it looks, and can comprise up to six different types of rubber, as well as varying styles of fabric and wire. How tires are stored, how they’re driven, and how hot or cold the roadways are when they are driven all affect tire life.

An alignment issue is death to tires, too, as varying forms of misalignment cause different types of uneven tread wear. 

2. Treadwear Rating

Take a look at the sidewall of a tire: you’ll see there’s a vast amount of information, including the tire size, aspect ratio, width, DOT classification and others. Possibly an important one, once you’ve chosen the right size, is the treadwear rating.

Below, tire sidewall graphic courtesy of Consumer Reports on the truth about treadwear.

treadwear rating reading sidewall

This is a number established by the U.S. National Highway Traffic and Safety Administration and applies a Uniform Tire Quality Grading to tires.

The first number is treadwear, and the higher the number, the longer the expected tread life. The number is a bit arbitrary, and testing, though ostensibly to NHTSA standards, is done by the tiremaker. The ratings can range from as low as 100 (for a high-performance tire where grip is the overriding concern) to 700 to 800 for standard passenger tires.

Yet, one 400-rated tire from one manufacturer may not be the same as a 400-rated tire from another. Treadwear is most instructive when comparing tires from the same manufacturer. Comparing tires from different manufacturers, not so much.

The best advice for shopping for tires is to start looking at prices when you think you might have six months remaining on your tires. If you see a deal, pounce.

How long tires really last depends on you (sorry)

In the end, determining the lifespan of your tires is up to you the driver, or your trusted mechanic.

The Quarter Test

In Canada, there’s the quarter test: hold a quarter, Queen facing you, and insert it Queen’s head down into the tread. If you cover up part of her head, you’re good. If you don’t, the tire should say goodbye.

So call up that Canadian cousin and ask for a quarter to ship south of the border.

Or check out this video debunking the Penny Tire Test. It’s about 5-minutes long and from 2007 – but hey, it still makes sense:

Treadwear Indicators

Tires typically have treadwear indicators, as well: the simplest are bars that are raised slightly from the bottoms of treads. You should consider these last-resort indications, because by the time your treadwear indicators show up, your tire is pretty close to bald.

Winter Tires: More to Think About

Winter tires are also a bit more complex, as they often employ two different grades of rubber for the tread blocks: softer, grippier rubber on top, harder rubber at the bottom. Once that soft, grippy rubber goes away, you no longer have winter tires. 

Tire Inflation

Inflation is critical to getting the most out of your tires: too much inflation can be as bad as too little. Both cause uneven tread wear, as well as increase the risk of either sidewall failure or a pinch failure.

According to this Edmunds feature on inflating tires, The Department of Transportation estimates that 5 million gallons of fuel a day are wasted due to low tire pressure.

Inflation is indicated in your owners manual or on the placard on the driver’s door jamb. Follow these, not what is on the tire. Your vehicle’s engineers chose these numbers given the engineering decisions applied to the suspension.

Cold Tires Work Best

It’s best to check these values when the tires are cold: driving creates heat, heat expands air and properly inflated tires can appear overinflated after driving. Tires typically lose one to two pounds of pressure per month, while weather changes can also affect inflation. When cold weather sets in, there’s a good chance you need to add air.

Tire Storage: Do it Right

Storage of tires also affects their lifespan. Tires mounted on rims should be stacked or hung by the rims. Tires not mounted can be stacked, but not in a high stack, maybe six tires maximum.

Unmounted tires should not be hung, as the sidewall can be irreparably distorted. Tires not mounted are best stored upright; a wall rack is handy. For the best storage, wrapping them tightly in dark, plastic bags is good, while sealing the bags and evacuating as much air as possible (you can use a vacuum) is best. An airtight seal helps prevent the oils in the rubber from evaporating.

3. Best Time to Buy Tires…

Discounts happen randomly throughout the year, often based on a tiremaker or retail chain needing to hit a certain number of sales, but April and October are also prime discount seasons, as tiremakers and retailers seek to capitalize on seasonal switchovers to boost sales.

Are you in the market for new tires? Goodyear is a trusted brand, offering decent deals throughout the year – and they now sell tires online so take a look here.

For buying winter tires, consider the key signal for switching into and out of winter mode: 45 Farenheit or 7 Celsius.

On the way into winter, that’s the temperature when summer tires start to harden, or glassify, and it’s also when they start to soften again in spring. So depending on where you live, switch to winter tires on or about the first day weather trends suggest mean daily temperatures at or below 45 Farenheit or 7 C, and vice-versa on the way out of winter. (In some parts of Canada in particular, those dates are Oct. 1 and April 30).

The best advice for shopping for tires is to start looking at prices when you think you might have six months remaining on your tires. If you see a deal, pounce. You don’t have to mount them right away.

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