WARNING Excessive heat from fire, brake malfunction, wheel bearing failure, tire failure or other sources may weaken the aluminum and cause the wheel/tire assembly to separate explosively. Exploding tire/wheel assemblies can cause serious injury or death. Therefore, it is critical that any wheel that has been exposed to excessive heat be immediately and permanently removed.

What is a heat indicator label?

A heat indicator label alerts whether a wheel has been in a thermal event that could compromise its integrity. While we cover additional methods that help identify this issue in our Wheel Service Manual, we found that a visual indicator is more effective when used by equipment operators. It ensures operators understand whether a wheel needs to be inspected for a thermal event.

Where is the heat indicator label located?

Forged aluminum wheels manufactured starting in January 2009 will have a 1-inch clear, round heat indicator located next to the roll stamp on the inside shown in Figure 1, as well as a similar 1-inch clear round heat indicator on the tire side drop well.

How does the heat indicator label work?

If either of these round labels show signs of blistering, or have a charred, blackened, or cracked appearance, this may indicate the wheel has been exposed to excessive heat.

IF ANY OF THE ABOVE CONDITIONS ARE SEEN, REMOVE THE WHEEL FROM SERVICE IMMEDIATELY AND PERFORM DIMENSIONAL CHECKS PER SECTION 3-4 IN THE ALCOA^® WHEEL SERVICE MANUAL. THIS INCLUDES ANY HEAT DAMAGE TO THE TIRE, DISCOLORATION TO THE WHEEL AND/OR BRAKE DRUM, AND ANY BURNT OR CHARRED LABELS.

Important to know:

1. Wheels must be inspected for exposure to excessive heat before being returned to service. A wheel that has been subjected to excessive heat may appear charred or burned, but it could also mistakenly appear to be in good condition if it has been cleaned.
2. Do not use any wheel that has been overheated regardless of appearance. Even if a wheel does not appear to be obviously burned, inspect the labels, tire bead, brake drum and high temperature nylon spacer for evidence of charring, melting, blistering, or burning.
3. Any wheel run with a flat tire longer than the time necessary to immediately pull off the road should be checked for excessive heat damage.
4. A wheel may discolor from excessive heat. It can show a dull grayish color and will not polish to a bright finish like an undamaged Alcoa^® wheel.

MORE RESOURCES:

Wheel Service Manual

Watch video about the Roll Stamp and the Heat Indicator Label.