Seating both beads correctly should minimize mounting-related bouncing or wobbling.
If the wheel is off-center with respect to the tire, there may be a bouncing-like ride disturbance, and eventually, irregular wear.
If the wheel is crooked with respect to the tire, there may be a vibration-like ride disturbance, together with rapid wear, irregular wear, or all three.
 Check the assembly for concentricity by using the tiny ring molded into the tire sidewall, observing its distance from the wheel flange.
Some OEM’s match the tire high point (indicated by a red dot) to the low point dimple on steel wheels.
If a tire has a red dot, but the wheel is aluminum or a steel wheel with no low point dimple, match the red dot to the valve stem.
All Bridgestone radials have a yellow dot, which should be matched to the valve stem location for best initial static balance.
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What does “concentric” mean?
In terms of tire mounting, “concentric” simply means that the center of the wheel or rim is in exactly the same place as the center of the tire mounted on it.
Why is this important?
Depending on how non-concentric the assembly is, drivers may or may not feel ride disturbances. If the mounting is bad enough, ride disturbance will be evident immediately.
More subtle mismounting may not be noticeable at first, but can lead to irregular wear initiation. As irregular wear progresses, it can cause ride disturbance. So, even though non-concentric mounting may not cause vibration immediately, the irregular wear it causes may do so later on.
Doesn’t the mounting process automatically make tires and wheels concentric?
Unfortunately, no. Both the tire and wheel must be clean and properly lubricated. Otherwise, the tire bead can get stuck in the wrong position on the rim flange before it is fully and concentrically seated.
What causes tires and wheels to be non-concentric?
Improper mounting procedures, including poor cleaning and inadequate lubrication are the most important factors. If the tire’s bead isn’t seated properly on the rim flange, the tire and wheel will end up being non-concentric.
In some cases, the assembly acts as if it were out-of-round. The result can be bouncing or thumping – like a tire with a flat spot from brake lock. Left untreated – like a flat spot – this condition can worsen, and may lead to severe irregular wear.
If the tire is crooked on the rim, the result can be like a bent axle or wheel. The tire may wobble and vibrate. That can cause rapid wear, irregular wear, or both.
What do I do if a mount isn’t concentric?
Break down the assembly and try again. Check tire and wheel for cleanliness. Relubricate both of them. Align the dots appropriately, (see pictures to left). Then, reseat the beads.
If that doesn’t get it, try rotating the tire 180 degrees with respect to the wheel, remount and check concentricity again. If you still have no luck, try another tire or another wheel. That may help you pinpoint the problem.
Does a non-concentric mount ever “fix” itself?
Never. But there is some good news: Once a tire is properly mounted, if you maintain proper air pressure, the tire and wheel will stay concentrically mounted.
Is there an easy way to remember all this?
Just remember “Clean, Lube, Align, Check.” Or, memorize the nonsense word “CLAC”, made from the first letters of each step. And, if you don’t already have a copy of our step-by-step video, Truck Tire Mounting for Customer Satisfaction, you can view it online or order a DVD for your shop. Just visit BridgestoneTrucktires.com and click on “Tools for Longer Wear.”
Please direct any technical questions on concentric mounting, or any other tire-related subject for that matter, to our engineering team at
1-800-847-3272, or drop us a line at “Ask the Tire Doctor” by clicking on “Contact Us.” |
