When to Replace Tires: Tread, Age and Damage

Tread depth is one of three reasons to replace a tire. Age and damage are the other two, and they catch people out.

Most people replace tires when the tread runs out. That is one of three legitimate reasons, and the other two get missed regularly.

Tread depth

Legal minimums exist and they are genuinely a minimum, not a target. Wet performance degrades substantially well before a tire reaches the legal limit, because tread depth is what evacuates water from the contact patch.

Wear bars molded into the grooves indicate the legal minimum — when the tread is level with them, the tire is done. A depth gauge gives you a real number and lets you plan rather than react.

Measure at several points across the tread and around the circumference. Uneven depth is itself a diagnostic about inflation, alignment or suspension.

Age

This is the one people do not think about. Rubber degrades with time and UV exposure regardless of use. A tire with plenty of tread can be too old to trust, and in West Texas sun that degradation runs faster than in a mild climate.

The DOT code on the sidewall ends with four digits: the week and year of manufacture. Check it on any tire you buy — including a spare, which frequently sits for years — and on the tires currently on a vehicle you bought used.

Signs of age: fine cracking in the sidewall or between tread blocks, a hardened surface, and a general loss of pliability.

Damage

Some damage ends a tire regardless of tread and age:

• Sidewall cuts, punctures or bulges. A bulge means the internal structure has failed. There is no repairing a sidewall.
• Separation — a visible ripple or a rhythmic thumping that speeds up with the vehicle
• Impact damage from a pothole or curb strike, which can break internal cords without an obvious external mark
• A tire that has been run flat, whose structure is compromised even if it looks fine
• Repairs outside the repairable area or too many repairs too close together

Replace in pairs, at minimum

Two new tires go on the rear regardless of drive configuration, because the rear having more grip than the front is far more controllable than the reverse. That surprises people and it is the standard recommendation.

On all-wheel-drive vehicles, mixing tread depths across axles can stress the driveline, and many manufacturers specify replacing all four. Check what your vehicle requires.

The spare

Check its pressure and its date code. A spare that has been ignored for eight years is not the backup you think you have, and finding that out on a shoulder outside Post is a bad afternoon.

Where we fit

Elite Tire & Brake sells, mounts and balances tires in our Lubbock shop and comes to you. Call (806) 458-2709.