Issue link: https://read.dmtmag.com/i/34500
TRAILER: Step-Shoulder/Localized Wear Shoulder Cupping (Condition Code 187/196) Appearance: Tire exhibits step-down wear on one or both shoulders or localized cupped out areas. Probable Cause: Damaged/bent trailer-axle, incorrect camber setting, alignment issue, LTL (Less than Truckload) operation, incorrect air pressure, suspension compliance. Analysis/Correction: Review tire application with tire manufacturer; review inflation maintenance procedures. Check trailer alignment for bent or worn parts, or consult trailer OE. Left Front Trailer Position (Original) Left Front Trailer Position (Rotated) Trailer Rotation: Irregular wear on the inside shoulder of trailer tires can be rectified by flipping the tire on the wheel, where the inner shoulder becomes the outside shoulder. Criss-cross rotation may also be helpful depending upon 1st and 2nd trailer axle wear-rates. Brake Skid (Condition Code 176) Appearance: A tire with brake drag is characterized by localized abrasion or flat spot if severe. If left in service, it may continue to grow across the face of the tread. Probable Cause: Tractor/trailer moved prior to system air pressure building up sufficiently to release parking brakes: resulting in dragging the tires or driver over-using hand or trailer brake. Analysis/Correction: Review driver tractor/trailer hook-up and departure instructions. The fleet yard mule driver can be a factor. If they are in a hurry to move trailers, they may pull away before the air pressure has built up sufficiently to release the brakes. If the flat spotting is minor, leave the tire in service. If tire induces vibration, has exposed steel or is lower than the minimum required tread depth, remove the tire from service. Even vehicles equipped with anti-lock brake systems (ABS) can experience flat spotting, depending on the number and placement of sensors and modulators used. 46 MICHELIN X One Tire Maintenance ® ®