Have you heard the one about the guy who changed the air in his tires from summer blend to winter blend every fall?

This inside joke for gearheads is like the ones about muffler bearings and blinker fluid. Who knew that Tire Pressure Monitoring Systems would come along and bring an acute need for seasonal attention to tire air pressure?

Tire pressure that was borderline acceptable in warm temperatures will turn on the TPMS warning lamp when it’s cold. Pressure has always dropped as temperature drops, but now drivers are aware of it. They line up outside my shop to inflate their tires on the first cold morning of fall.

Whether the TPMS lamp pops on or not, fall is the time to have cars checked for winter. Maintenance inspections usually accompany oil changes, but even if the oil change isn’t due by mileage, the inspection should be done due to time of year.

Cold temperatures and winter roads will stress the entire vehicle. And if any system fails, it is more dangerous to be stranded in bad weather than in fair weather.

Certain items are especially pertinent to safe winter driving, though: The battery, starting system, and charging system should all be tested before winter, because battery performance declines in cold temperatures. Antifreeze should be accurately measured for a maximum freezing point of -34 degrees F. Obviously the heat and defroster better work, too.

To get through the snow, tire tread and four-wheel-drive systems are critical. Studded snow tires can be used in Maine starting Oct. 1. Tires with tread near the legal limit of 2/32 inch might warrant replacement at the beginning of snow season.

Fluids in the gearboxes should be inspected, along with universal joints, and wheel hubs. Stability control and its related functions of antilock brakes and traction control can be electronically tested with a scan tool, even if road conditions are still too good for a performance check.

Rubber parts will be less flexible when cold, so belts and wipers need attention. Modern belt wear must be measured with a tool, rather than visually inspected for cracks. When wipers deteriorate, the first streak always seems to land in the driver’s line of vision instead of the passenger side. To avoid this aggravation, I recommend changing them every fall, whether they look as if they need it or not.

Functioning washer pumps are no longer required by law, but it’s impossible to get through a Maine winter without flushing the road salt off the windshield. It’s smart to stock up with an extra gallon of strong washer fluid with a low freezing point.

Lights are important for visibility on a snowy day. Finally, if all else fails, the flashers better work, so check the functions of all the exterior lights.

Many of the tests I mentioned require specialty tools and a high level of expertise, so I recommend getting a professional opinion. Technicians often perform these seasonal inspections at no cost or for a low fee, especially if you are a regular customer. Their hope is that customers will buy services that are indicated by the inspections.

When you are driving in bad weather, confidence in the vehicle is well worth the price of professional service. By comparison, the cost of not being prepared for inclement weather could be monumental.

Winter driving is serious business, but it helps to have a sense of humor. With respect to the temperature-pressure relationship: If your tires need air, ask your technician if you can borrow some for the cold winter, and promise to bring it back in spring when you’re done with it.


Ruth Morrison is an Automotive Technology Instructor and Department Chair at Southern Maine Community College. She holds certification as an ASE Master Technician and Advanced Level Specialist and was a former Ford Senior Master Technician.  

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