Sidewall Problems

The Sidewall tool helps drivers assess what they're seeing on the tire's sidewall — distinguishing between normal features (indentations from cord overlap, antiozonant browning) and safety concerns (bulges, cuts, cracking). It asks about the shape, location, and appearance of the anomaly and provides guidance on whether it's harmless, worth monitoring, or requires immediate action.

The tool distinguishes between two fundamentally different conditions: indentations (normal) and bulges (not normal). An indentation is a slight depression where cords overlap inside the tire — it's a structural feature, not a defect. A bulge or bubble is a protrusion indicating that air has infiltrated between damaged cords. The tool will direct an outward bulge toward immediate replacement and professional inspection.

The sidewall flexes constantly with every rotation of the tire — it bends and straightens thousands of times per mile. Any repair material applied to this flexing surface would be subjected to the same cyclic stress and would eventually detach, causing a sudden failure. Sidewall damage means the structural integrity of the tire is compromised. Replacement is not optional for a tire with a confirmed bulge — driving on it risks a sudden blowout.

The severity depends on the depth and distribution. Fine surface cracking across the sidewall is a sign of age-related rubber oxidation and ozone exposure — it's common in older tires and is why Michelin recommends inspection after five years and replacement by ten. If the cracks are fine and shallow, they indicate age but may not be an immediate safety issue. If they open visibly when the tire is flexed, or if they're deep or numerous, the tire has degraded past safe use and should be replaced.

Yes, and it's worth doing. Spare tires are often out of sight for years and can develop age-related cracking or damage without the driver noticing. Check the spare's sidewall condition alongside the four regular tires, particularly if the vehicle is older. A spare that has visible sidewall cracking or is past ten years from its manufacture date should be replaced — a damaged spare is no help in an emergency.

Don't drive on the tire if the tool has flagged a bulge or severe damage. Fit the spare and take the damaged tire to an authorized Michelin retailer for assessment. If no spare is available and you must drive, keep the journey very short and at low speed to get to the nearest service center. A tire with confirmed sidewall damage is not safe for extended or normal-speed use.