In fact, tire performance is critical for the performance and safety of your vehicle.

But even the highest quality tires wear out over time and must be replaced. As the Ontario Ministry of Transportation points out, worn-out tires are more prone to cracks, have reduction traction on roads, and may even fail completely while in use. Don’t let aged tires compromise your safety and the safety of your passengers. Use these five signs as a cue that it’s time to replace your tires:

Sign #1: Their Tread is Less Than 1.5 millimetres

When your tire’s tread is less than 1.5 millimetres deep, it’s a sure sign that the time has come to replace them.

How do you find out whether your tread has reached critically low levels? A simple “penny test” will help you to find out.

Place a quarter (caribou-side up) into one of your tire’s tread grooves. Be sure that the caribou’s nose faces down. If you’re able to see the tip of the caribou’s nose, then it’s time to replace your tires!

Remember: winter tires may be hardy enough to get through a Canadian winter, but they still need replacing, just like all-seasons. Replace your winter tires with a fresh set when their tread has worn to 6/32nds of an inch.

Sign #2: You Notice Abnormal Bulges or Bumps

If you notice any tires with abnormal bumps, knots, or bulges, then take heed – these will need to be replaced. Bulges or bubbles in your tires can be caused by driving over curbs or through large potholes. Driving with low tire pressure can also cause knots or bumps in your tires.

If you find a bulge in the tire’s sidewall – the side of your tire that is visible and includes the brand name – then this is an indication that the internal frame of the tire has been compromised with cracks or other types of damage. This means that air pressure has leaked from the rigid internal frame to the flexible outer layer of the tire itself.

If you notice bumps, bulges, or bubbles in your tires, then you should not continue driving with the affected tires, as their structural integrity has most likely been greatly reduced. This increases the chances of your tires failing as you reach high speeds – to avoid this dangerous risk, replace the affected tires as soon as possible.

Sign #3: Your Tread Wear Bar is Visible

This sign of necessary tire replacement is the easiest one to recognize. Take a look at your tires – the small bridges between the treads, forming between treads or running across the tires, are the “tread wear bars.”

These will become flush with the tire’s tread as the tire wears over time. When the tread wear bars become completely even with the tire’s actual tread, it’s a sure sign that your tires need replacing.

Sign #4: Your Tire is Punctured

If your tire has been punctured, you must take careful consideration to determine whether the affected tire can be repaired, or if a complete replacement is necessary.

If you find that one or more of your tires has a puncture, then you should inspect the puncture as soon as possible. If it is six millimeters or less in depth, then your tire can be safely repaired.

However, if the tire is affected by a puncture that is more than six millimeters deep, then you should replace your tire as soon as possible.

What’s more, if one or more of your tires are punctured in several places, and these puncture holes are close enough that any repairs would overlap, then a replacement is necessary.

Sign #5: It’s Been More Than 10 Years

If it’s been a decade since you last replaced your tires, it’s time to get yourself a new set of wheels!

If your tires are more than ten years old, then most experts recommend that you replace them, even if they have no visible damage. Although they may look like they’re in good condition, and their tread wear bars have not been worn down, if your tires have not been replaced for ten years after their manufacture date, the safest option is to replace all four of them.

What’s more, after five years of use, you should be sure to get your tires inspected yearly by a professional auto mechanic.