Kelly's Garage - Active Green and Ross - December 2011




Do you have your Christmas tree up? Have you wrapped all of the gifts, do you have your winter tires installed?  This is a crazy time of year for everyone getting ready for the holidays.  I sure hope you already have your winter tires installed! If you need to buy winter tires there is still time to buy 4 Michelin tires and enter to win a Fiat 500 in the Retire Your Ride promotion at Active Green and Ross.

In the meantime, I wanted to wish you and your family Happy Holidays and be safe on the road.



The first vehicle to use tire pressure sensors was the Porsche 959 in 1986                         

This month's topic: Tire Pressure Sensors

Since we are getting into a time of year where we are going to see the air temperature drop significantly I thought I would talk about Tire Pressure sensors.   Tire pressure sensors (TPMS) have been around since the 1980’s. They became law in the US in September of 2007 under the “Tread Act”.  It is not yet law in Canada but many vehicles have these sensors. 

What does the tire pressure sensor do?  Basically, it monitors the air pressure in your tire and sends a message to the computer.  There are two types of sensors: Direct and Indirect.  Many of us have direct sensors, meaning that we have one inside each wheel.  In fact, when you check your tire pressure you are actually putting your tire pressure gauge onto the sensor itself.  Some vehicles use an indirect sensor instead.  This type of system doesn’t actually measure the air pressure but uses the revolutions of the tire to determine if it is properly inflated.

Tire pressure sensors can be a great aid since the days of kicking the tire to see if it low are pretty much gone.   You can’t really tell if the tire is low by visually looking at it unless it is completely flat!  If your vehicle doesn’t come with TPMS sensors you could always have them installed afterwards.  Speak to you local Active Green and Ross store about what options are available.

I often hear people complaining about their low tire pressure light coming on more often in the winter.  I’ve included a picture of what the light looks like just in case you’re not sure which one I am talking about.  The reason why the light comes on more often in the winter is because of the temperature fluctuations we experience.  For every 5 degrees Celsius drop in temperature our tires will decrease by 1 PSI (pound per square inch)  Many low tire pressure warning systems are  designed to come on when your tires are 25% under-inflated.  For example  if your tires are supposed to be 32 PSI the light will come on when they are down to 24 PSI.   This is pretty significant! 

One of the challenges people have when they buy an extra set of winter tires and rims is whether to purchase another set of TPMS sensors.  This can add from $50 to $100 per wheel.  Many people choose to forgo the expense of the TPMS sensor and deal with the light being on their dash all of the time.  If you are one of these people who decide to do this please make sure you discuss with your Active Green and Ross service advisor whether this will impact your vehicle or not?  With some manufacturers when the computer senses the TPMS light being on, it will put the vehicle into what is known as a “limp” mode and now allow it to go over 50 km/hr.  Fortunately, I don’t think this happens on a lot of vehicles but it’s better to be safe than sorry.

Here are a couple of last things to know about tire pressure sensors.  First, you should use plastic valve stem caps rather than metal caps as this can fuse the valve stem with the valve core and cause even bigger problems.  Lastly,  if you have a direct system they have batteries.  Do batteries last forever? No.  So if you find your tire pressure light on all of the time and you’ve checked your pressures and they are good, you could have an issue with the sensor and or the batteries.  These batteries can’t be replaced.   The whole sensor must be replaced.

Tire pressure sensors are great as they help keep us safe on the road but like anything else on our vehicle they will need replacement once they stop functioning.

Take care of your car and it will take care of you!

This months photo:

Example of direct tire pressure sensor     

Low Tire Pressure Symbol



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