What is the 45° rule?

Gary Jaffarian explains the important 45° rule and discusses the difference between snow and all-season tires and why you may want snow tires this season.

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When dealing with the snow we just experienced this past weekend, your tires and brakes are the most important aspects of your vehicle for safe driving. On Saturday night after the roads were cleared, I was driving slowly on a main street and someone pulled out of an adjacent restaurant parking lot too quickly and made the turn onto the main road ahead of me. I witnessed him doing a 180-degree spin-out. Fortunately, I had time to stop and wait until he turned his car back around.

My initial thoughts: “He doesn’t know how to drive in this weather; he didn’t read my Ask Gary blog last week on avoiding a skid; and he may need new tires.”

While many all-season tires suffice, the 45° rule is that winter tires stay flexible at 45° or below, while other tires will harden, reducing traction. Therefore, anyone driving consistently in lower temps, which we all do, will benefit from winter tires.

What separates winter tires (generally called snow tires) from the all-season tires?
• There is a special tread pattern for rain, light snow and mud.winter-snow-tires
• Deep grooves are for deep snow, that allows the tires to dig in and trap the snow in the grooves to help you continue moving forward.
• They are made of a special rubber material to stay flexible in cold temperatures.
• Winter tires are covered with small slits called “sipes” that create multiple edges that help grip wet, snowy, slushy and icy roads.
• They have a winter-specific tread pattern.

Proven winter performance tires are marked with mountain and snowflake symbols or an Alpine symbol, meaning they meet or exceed the industry requirements to be called winter tires.

All-season tires are built to handle a variety of road conditions – dry roads, wet roads, and in many cases, light snow. The tread compound of all-season tires can harden in low temperatures (lower than 45°), so there’s less traction between the road and your tires. Tire industry experts, including our Parts Department Manager, Walter Sazo, recommend winter tires in Northern climates like New England.

All-wheel drive and four-wheel drive improve traction by sending power to all four wheels when you accelerate (instead of just two wheels, as in front- or rear-wheel drive). But 4-wheel drive or all-wheel drive doesn’t help at all once you put on the brakes. Winter tires improve traction whether you’re accelerating, turning, or braking, according to tirebuyer.com.

“Winter tires should only be installed in sets of four, regardless of whether your vehicle is front-wheel drive, rear-wheel drive, or all-wheel drive. Using two different types of tires can give your vehicle a “split personality” where the front and rear are not working together. For the best handling, control, and safety in tough cold-weather conditions, we strongly recommend using four winter tires,” tirebuyer.com advises. “Plus, if you were to put two snow tires on the front of your car, and keep your all-season tires on the back, your all-season tires wouldn’t wear evenly.”

check-tire-tread-pennyNo matter which tires you have on your vehicle, be certain they are not worn. It’s best to have them evaluated by a service technician, but if you would like to check them yourself, be sure to do the penny or quarter tire tread test.


Most important tips for tires:
• Get them checked if you hear thumping—it’s a sign of uneven wear.
• Be certain the tire pressure is inflated according to the manufacturer’s recommendation for the season, usually listed on the label on the driver’s side door jam.
• Have tires rotated every 5-10,000 miles for even wear.
• Be sure to purchase the right size and brands recommended by the manufacturer.
• I’ve prepared a brief You Tube video (click here to watch) on how to know when you need new tires.

If you aren’t sure if you need new tires, come to our Jaffarian Volvo Toyota Service camry-insnowDepartment or our Parts Department and we will be happy to give you an objective opinion or help you choose the absolute right tire for your vehicle.

There’s much more snow ahead of us this season, so take it slow on snowy roads. There were too many accidents and deaths on the road this past week in the country because of inclement weather. If you can stay home during the worst part of a snowstorm, then stay in until the roads are plowed and treated.

Ask Gary Jaffarian




Gary Jaffarian

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