Prepare your car to drive in the rain

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A vehicle’s tires can often go overlooked by drivers in everyday life. It almost feels like checking the bottom of your shoe before you go on a walk — you just don’t think about it much – until it becomes a problem.

With winter in full-effect and spring fast-approaching, expect wet roads to be the norm for months to come in western Washington. To prepare for the wet conditions, drivers should consider their options regarding the best tire to suit their needs.

Most car tires are made the same way, with two main differences setting them apart. The chemical makeup of the rubber used for the tire and the tread designs on the outside of the tire account for the differences in use. Certain chemical makeups are better for wet conditions, while others are better for dry conditions. Different tread designs deal with water or moisture on the road in different ways. Deeper, wider treads push water out from under the tire, while a flat, slick tire can’t displace water much at all but has increased traction on dry roads.

Passenger vehicles are usually equipped with one of three main types of tires; either summer tires, all-season tires, or winter/snow tires. The names can be deceiving. Summer tires are best for driving in wet conditions. Their rubber is composed of chemical compounds made to stick to wet pavement and the treads are designed to push as much water as possible away from the “contact patch” where the tire meets the road. All-terrain tires are designed to work in dry, wet, and snowy conditions, but their versatility means compromising performance in all areas. Winter/snow tires are meant for primarily snowy conditions.

No matter what kind of tires are on your car, having the proper level of tread depth is key to being able to control the vehicle, stop quickly, and prevent accidents. Tread depth decreases over time as a tire gets worn down from use. Most new tires for passenger cars average a tread depth of 10/32” to 11/32.” Snow tires are typically deeper. In Washington state, the tread depth is legally allowed to be 2/32” at the lowest.

In a brake-test conducted by Tire Rack, new tires with 10/32” tread, worn tires with 4/32” tread, and tires with legal-lowest 2/32” tread were studied to find out the average stopping distance at each level of wear. They used a 2006 BMW 325i with 4-wheel vented disc brakes and an Antilock Braking System, equipping it with the different tires and testing them in wet driving/braking conditions. When stopping from 70 mph, they found that the new tires averaged a stopping distance of 195.2 feet in 3.7 seconds. The worn tires took 4.7 seconds and 290 feet to stop, and the 2/32” tread tires took an incredible 378.8 feet and 5.9 seconds to stop. That puts drivers with almost-worn-out tires at over a 183 foot disadvantage than drivers with new tires while in wet driving conditions!

Tire manufacturer Michelin debuted its new Premier A/S tire at the North American International Auto Show in Detroit in January 2014. The main tread channels on the tire actually get wider with wear, helping the tire to keep its grip even as the tread level decreases. Traditionally, tire treads are gouged in a V-shape with the widest opening at the top, prompting the treads to displace less water as they get shallower. Michelin flipped that V-shape (and they’re keeping the secret of how) so that as the treads get shallower they can continue to displace water from an increasingly wide channel. The new tire also has more than 150 “emerging-grooves” that present themselves as the tread wears down and help the tire keep its grip. The new tire is made from a “proprietary rubber compound with high amounts of silica and sunflower oil,” according to a press release from Michelin. “The silica provides the bonding strength and adherence to keep the tread on the road for high traction in wet conditions. The sunflower oil allows the tire to grip on wet roads at lower temperatures.” The tread on Goodyear’s Assurance TripleTred All-Season tire functions in a similar way.

How to check your car tires

  • Check for proper inflation. Even tires with the most advanced tread and composition technology can be useless if they are not inflated properly. An underinflated tire with carry most of a car’s weight on the outside shoulders of the tire, leaving less weight and putting less pressure on the center of the tire. This uneven distribution of weight can cause even the best rain-tire to hydroplane on puddles because the treads that push the water away from the tire are not pressing down on the ground, preventing them from doing their job.
  • Check the depth of tread. Testing the tread on car tires is simple if you have some spare coins around. Stick a penny, with the top of Lincoln’s head pointing towards the center of the wheel, in a few different areas of your tread channel. If the top of his head is covered at all then you have more than 2/32” of tread left. Do the same with a quarter and Washington’s head. If his head is covered than you have more than 4/32” of tread left. Flip the penny over, and stick the Lincoln Memorial in that tread top-first. If the top of the memorial is covered, you have more than 6/32” of tread left.

Consult your car’s owner’s manual to find the proper tire pressure and tire size for your car, and to see how often to rotate the tires.

No matter how fancy your tires are, always drive with respect to the conditions you’re in, and realize others aren’t always totally prepared for poor driving conditions.

Questions? We know a lot about car safety. Call us at 206-285-1743.