Every quality tire in our modern age features numerous technologies designed to optimize traction and improve road safety. But there’s one basic design factor that arguably trumps them all that no amount of tire technology can overcome: Tread depth.
Why is tire tread depth so critical?
When roads are wet, slush- or snow-covered, tire tread design comes into focus. The channels and grooves in your tires aren’t for looks (although, some designs are pretty darn cool), they serve the purpose of “evacuating” precipitation from the tire contact patch as the tire rolls, and therefore keeping the tread in closer contact with the road surface. Needless to say, when you turn the wheel or hit the brakes, the connection between your tires and the road is crucial; it’s your fundamental point of control.
If you’ve run a set of tires down to minimum tread depth or even lower, you might have experienced the hazardous loss of traction termed “hydroplaning.”
Hydroplaning occurs when tire tread effectively becomes disconnected from the road surface because a layer of water (or wintry precipitation) actually lifts the tire off of the road. The result is a complete loss of traction and control and a vehicle that is entirely unresponsive to your inputs.
“…tread depth determines how much water a tire can take up and disperse from beneath the contact patch. The less tread you have remaining, the more likely it is that a wedge of water will build up ahead of the tire.” – Continental-Tires.com
Continental has called attention to a recent test conducted with Autobild that focused on the issue of tread depth and hydroplaning. The test served as an important reminder that even top tier modern tires begin to steadily lose traction as the tire tread wears. And once tires reach minimum tread depth, their traction is hazardously compromised as compared to tires at full tread depth.
In the test, emergency braking was conducted from a speed of 75 mph in wet conditions. The braking distances varied substantially according to tire tread depth.
|Tire status||Stopping distance|
|Partially worn (3 mm)||407 ft.|
|Minimum tread (1.6 mm)||508 ft.|
That’s a braking distance difference of 314 ft. between new and fully worn tires. To put that distance into context, 314 ft. is about 21 car lengths. And to translate the performance difference to a real-world emergency braking situation in wet conditions: In the distance that’s required for a vehicle on new tires to come to a complete stop, the vehicle with fully worn tires would still be traveling at a high rate of speed and strike a vehicle or object ahead at 65 mph.
“The test drivers’ conclusion was unequivocal: Only new tires offer the greatest reserves of safety in the wet. Running tires down to 3 mm of tread is acceptable. But with the legal minimum tread depth of 1.6 mm, things get dangerous.” – Continental-Tires.com
We certainly understand drivers wanting to achieve the most tire life and value for money from their tires. But the Continental test is a sobering reminder that even the very best tires cannot deliver sufficient traction indefinitely. If you’re sensing a severe loss of traction with worn tires, and even if there is technically life/tread depth remaining, trust your instincts and act to replace them.
We’ve made it simple for everyone to stay up to date on their tire tread depth and overall condition, and better ensure tire safety. See details in our Quick tire safety check.