The case of road groove wander


Tom B. writes by email: “I have an Acura and I purchased new tires. Immediately on my way home I experienced a very squirrely and unstable feeling that made me immediately slow down and wonder if they tightened my wheels properly. After a few days of driving I discovered the unstable feeling was due to concrete road surfaces with grooves in them for water. It appears that the tires are catching the grooves and trying to steer the car. I would like your thoughts, especially on the theory that the problem is the tires and different tires would not do this.”


I asked my son Brad, who is a tire engineer in Akron, to see what his thoughts were. Here is his response: “I looked at this tire design and I’m not surprised at all that it’s sensitive to road grooves. It’s called (not surprisingly) Road Groove Wander. What you describe is correct. It is tread geometry-related. Basically, the circumferential grooves are all straight so they “hook” the road grooves. The road grooves look straight but have enough wander to pull the car around. That size must be just right for more than one groove to line up with the road grooves. We use modeling tools to predict this wander.

The same tire in a different width might be fine or that whole tire line might be sensitive. It depends on how the groove spacing lines up. Your tires on another vehicle might also be fine. The fix is to replace the tires with something else. Being new tires, I’m sure the dealer will work with you.”

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