- 5 Min Read
- By: Alex Fiehl
How to Tell When Tires Should Be Replaced
Tires should be checked monthly to ensure they are in good condition to keep you safe and out of trouble. It’s the only thing between you and the road. Avoiding a crash altogether with good tires is often better than resorting to your vehicle’s ability to protect you during a crash.
Are there any leaks? Does your car have a tire pressure monitoring system (TPMS) giving off warning alerts?
Incorrect tire pressure increases tire wear and can reduce road grip. Simply eyeballing the tires to see if they’re low or kicking the sidewalls for stiff pressure is better than ignoring them altogether, but you should take 5 minutes each month to actually measure each tire using a quality air pressure gauge. Overinflation or underinflation causes improper contact with the ground and adversely affect your tire tread’s wear pattern over time, reducing its lifespan and likely voiding your tire’s warranty. Underinflation also increases fuel consumption.
Be careful if you have run-flat tires and ensure you’re more diligent with checking their air pressures. They may appear fine but if it’s low and your TPMS isn’t working for some reason it can eventually fail and become a much bigger issue.
If one tire is significantly lower than the others then get air added to the car’s tire pressure specification. Most cars seem to be around 32 PSI or so when they’re cold (tires that are the same temperature as the outside air temperature). Check your car’s tire information label usually located in the driver’s door frame.
Monitor that tire by rechecking on a daily basis: you could have a slow leak that may leave you stranded. Punctures that cause leaks can be repaired but not if it’s too large or close to (or located at) the tire’s sidewall.
Sometimes TPMS alerts happen because a battery in the sensor may have died. They usually last about 10 years and the entire sensor may need to be replaced if the battery can’t be swapped. Your tire may have sufficient air pressure to keep you driving safely but if you don’t fix the problem you lose out on a valuable car feature to ensure you’re always safe.
Never reduce the pressure of a hot tire. Tire pressure increases as the tire gets warm.
Is the depth more than 2/32”? Are you seeing treadwear indicators at the tire’s contact surface in 3 or more locations? Does each tire have an even wear pattern? When was the last time the tires were rotated? Did the wheels ever get aligned?
Tread depth ensures the tire’s ability to channel away enough rain+snow to ensure sufficient road grip. The tread wear pattern should be even across the tire’s contact surface with the road to maximize its grip. Look for low/balding spots: if you discover significant differences you’ll need to try and determine the its root cause before replacing the tire, else your new tire may wear out early in the same way. Avoid driving on tires that have any bald spots as it won’t have much grip in rain/snow and can hydroplane.
Check your owners manual for instructions on when+how to rotate your tires. Keep a log so you ensure scheduled rotations are completed to maintain uniform wear on all tires.
Scheduled wheel alignment is not usually needed (unless you’ve completed some suspension work like changing tie rod ends). However, if you notice unusual tire wear or your vehicle is pulling one way or the other, the car’s wheel alignment may need to be reset.
Is the rubber still pliable? Are there any visible cracks? Any bumps/bulges or splits/tears? Any cord or fabric showing through the tire’s rubber?
Check for cracks, bumps or tears. I had a tire once where a chunk of the sidewall went missing somehow. While I could still drive on it the tire shop deemed it unsafe and replaced it under a pro-rated warranty as it was still in effect.
Tread separation is unsafe and can cause serious life-threatening accidents + vehicle damage. It’s seemingly rare but possible if you ignore your tires’ health.
When were they new? Are they out of warranty?
Tires gradually lose their grip with age and should be regarded as perishable goods. The rubber becomes hard and their friction properties are reduced. This is particularly true on winter tires. You can check your tire’s sidewall markings for its manufactured date by decoding the listed numbers.
Check your owners manual (or tire manufacturer’s website) to see if there’s any reference to how long tires are recommended for use. There are differences on this point varying from 6-10 years because it’s hard to tell how the tires were exposed to varying temperatures, conditions, pollutants, etc. Rule of thumb is to do an annual check for the tire’s condition and determine from there if it’s time for replacement.
Are they sized to match your car’s OEM specification?
Check if your owners manual or tire information label for the correct tire size spec. Running a difference size can negatively affect the car’s directional stability, steering and braking in both wet and dry conditions.
They they may look “cool” to some, but wide tires with side walls that are too low can be damaged in potholes, cause springs, shock absorbers and wheel bearings and body mountings to be overloaded and affect the function of the car's traction control system (if equipped). I tried low-profile tires once and experienced a blowout when I hit a pothole: this was not fun and I quit using them.
Are they the same make+model? Are winter tires being driven in the summer, or vice-versa?
Mixing tires could cause you to lose control while driving. If you mix tires of different sizes or types (radial and belted tires), the vehicle may not handle properly, and you could have a crash. Using tires of different sizes may also cause damage to your vehicle. Be sure to use the same size and type tires on all wheels. It’s ok to drive with your compact spare temporarily as it was designed for short emergency use to get you to a tire shop.
All-season tires are designed to be used year-round. Winter tires are designed+formulated for increased adhesion in cold temperatures but don’t grip as well in the summer. The same goes the other way around for summer tires being used in the winter.
Does your care come with one? Have you checked that it’s actually there? Was it ever used?
Don’t forget the emergency spare tire and check for the above points. Sometimes this tire gets ignored. I’ve had a few people get stranded as they thought they had a spare tire but it wasn’t there for some reason. While you’re checking for it, ensure you’ve also got the tools to jack up the car and swap the wheels as specified in the owners manual.
Note that the tire pressure for a smaller spare tire is usually higher. Check your owners manual or tire information label in the drivers door frame to get the right pressure spec. For example, the spare tire pressure on a Saab 9-3 is 60 PSI, almost double that of my regular tires.
If the tire was ever used, it should have been for temporary emergency use in getting enough distance to arrive at a tire shop. They usually don’t last more than a few thousand miles. Sadly I occasionally see instances where drivers negligently use a spare tire for much longer durations or at speeds beyond its safety rating which is unsafe to anyone around the moving vehicle.
If in doubt with any of these, visit a reputable tire shop and get a professional opinion.
Alex is FCP’s Blog Editor and a Desktop Engineer from Endwell, NY. He has over 9 years of experience working on a wide array of import makes, but has found his home with European cars. With a BMW and Volvo at home, the garage is always busy.