What influence does the tire profile have on the braking distance? – Jalopnik

Tire tread gives your car grip and control, but if the tires go bald you won’t stop, you’ll probably skid to the sound of pure regret. Those grooves help channel water, slush, debris, and anything else that tries to sneak between the rubber and the pavement, while the tread peaks help your vehicle grip the surface. As the tread wears you lose that grip in dry conditions, but in wet conditions it gets worse. A study released by AAA revealed that driving with moderately bald tires on wet highways can increase braking distances by as much as 43%.

Tire Rack’s wet braking tests with a 2006 BMW 325i showed how frightening real differences in tread depth can be. With brand new tires, the car pulled itself from 120 km/h to a stop in 60 meters and 3.7 seconds. At 2/32 of an inch, the legal minimum for tire tread depth, the vehicle took 378.8 feet and 5.9 seconds to come to a complete stop. Drivers in the test described braking as noticeably slowed. Even with another 4/32 inch tread, the car took 290 feet and 4.7 seconds to stop. It was the same car, same brakes and same driver, showing how, when it comes to worn tread, the difference between a safe stop and a dangerous crash can be just a few millimeters of rubber. Mandatory automated braking requirements may not be far away, but you still need sufficient tread depth for the technology to work properly.

Tire tread definitely affects how well your car stops, but that simple statement doesn’t even cover the full picture. Tire treads come in different styles, including directional, symmetrical and asymmetrical, and the tread has a specific depth. Essentially, tread depth is the distance between the grooves that channel water and the raised peaks that grip the road surface. Most new tires start with a tread depth of about 10/32 to 11/32 inches. As you rack up the miles, heat, friction and road grime slowly shave off the tread. Once you get below 4/32 of an inch, traction drops off quickly. With a length of 2/32 of an inch, you will hardly get stuck, especially in the rain.

Tests comparing different tread depths have shown that braking distances increase alarmingly as tires wear. According to a study by Hunter Engineering FirmOn average, a car with new tires and a tread depth of 10/32 inches stops at 234 feet. Knock the tread depth back to 6/32 of an inch and the vehicle stops at 253 feet. By the time you reach the minimum 2/32 of an inch, you will slide 356 feet after braking.

It is clear that worn tire tread is dangerous. But what does a smart driver do? Keep an eye on the tread depth – and not just visually. By using a simple coin to test the tread or purchasing a measuring tool, you can see the warning signs long before the tire is dead.

The old-fashioned penny test is still one of the easiest ways to find out if your tires are worn out. Turn a penny upside down and insert it into the groove of the tire. If you can see the top of Lincoln’s head, congratulations, because you’ve reached 2/32 of an inch of tread and it’s time to start buying new tires. If Lincoln’s hairline is hidden, you still have some tire life left. But legal doesn’t mean safe. Below 4/32 of an inch, your braking distance increases and hydroplaning becomes far too easy. That’s where the quarter test comes in handy. Drop George Washington headfirst, and if you can see his scalp, you’re less than 4 inches tall and have limited traction.

If you don’t have the money (understandable, because new cars are too expensive), check for wear bars – those little raised strips between the grooves. Once they are flush with the tread, your tires are ready. However, for the most accurate reading, you can use a tread depth gauge. Check often and in multiple places. Tires wear unevenly and your safety literally depends on those few millimeters of rubber.

Finally, think about your tire choice. Some tires are built to maintain better traction on wet surfaces and come with special tread patterns. So if you live in a rainy climate, prioritize these features when shopping. Consider all-season tires instead of all-terrain tires, as they provide a good spot for all-around use.