Can we use those buttons for wear bars?
All Bridgestone truck tires have "wear bars." These are ridges in the
grooves that tell you when the tread is worn to 2/32".
Their location is indicated by a small triangle molded into the shoulder.
The buttons at the bottoms of some tread grooves have a totally different purpose. Their job is to prevent stones from getting lodged in the grooves, then being driven through the undertread layer until they bruise the belts.
Some companies call these "stone ejectors." Bridgestone prefers the word "rejectors," because they don't really "eject" stones. Instead, they wiggle and squirm against them, helping to prevent them from getting stuck.
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"Stone rejectors," found on many Bridgestone tires, are designed to prevent stones from lodging in tread grooves and damaging casings. |
On a Bridgestone M726 EL, they stand about 7/32" off the bottom of the grooves. So, when the blocks are worn to their level, you have about 7/32" remaining tread depth, far more than the 2/32" allowed by law.
If you pull tires early to protect casings for retreading, you may be able to use these stone rejectors as a guide. With 7/32" remaining tread depth, you have an excellent chance of avoiding casing damage that could prevent successful retreading.
So they aren't wear bars, but they could be useful for something more than just rejecting stones.  |
