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Where The Rubber Literally Hits The Road

driving-in-rain-02Take a look at your average sized postcard.  Not very big, is it? Now imagine four of them at the corners of something measuring about 3 × 2 metres or so. They don’t take up much of that space. However, in the typical car, this is the sort of area your tyres take up when they actually contact the road: roughly the size of a postcard. Of course, a fatter tyre will have more surface area contacting the ground – they don’t just look good.

Those of you who fell asleep in high school science class when they talked about friction had better wake up and pay attention now.  Everything to do with staying safe on the road is to do with friction.  Inside an engine or a car, friction is bad news.  It makes an engine less efficient and wears things out more quickly – which is why you need to keep up the fluids and why you should check your oil regularly. However, you need friction and lots of it with your wheels to help your tyres grip the road and to help your brakes stop the wheels spinning.

It’s not all that smart to head out onto the road to get an idea of how lack of friction and low grip affects your turning ability.  So try a simple experiment on a piece of smooth, freshly polished floor – a school corridor or a big kitchen will do.  Set up a slalom course with lots of sharp twists and turns. Also include a track segment where you have to run full speed, then stop sharply.  First of all, simulate ordinary conditions with good tyres by running this course wearing sneakers with lots of tread.  Not too hard, is it?  Next, have a go at simulating the effect of tyres with little or no tread: take your shoes off and do it in your socks.  Sue yourself for damages if you fall over or crash into a wall.  Lastly, pour water all over the floor and try again, either with the sneakers or without the sneakers.  You can probably think of some other simulations to try, such as running the course in high heels (space saver tyres), pouring oil over the floor, having one shoe with tread and one without tread, etc.  However, somebody’s probably going to complain about what you’re doing to the floor at this point.  But you get the picture.

The point of this crazy exercise is to demonstrate that if your tyres are worn or if the road is wet, you are going to lose control or not stop in time when braking. Your car might have all the safety devices in the world – traction control, EBD, lane change warnings, collision avoidance systems, rollover protection and all the rest of it – but if you’ve forgotten to check your tyre tread, all these extra bits won’t do an awful lot.

There are four golden rules to making sure that your tyres stay on the road, gripping nicely during all the manoeuvres you put it through (heck, you bought a Porsche 911 because it was fun to drive around corners, didn’t you?):

  1. Check your tread depth.  The grooves should be no less than 2 mm deep. A lot of tyre shops have little cards you can use to check tread depth, but you can also make your own by playing around with a ruler, a vivid pen and a tag off a packet of sliced bread.  Do this regularly – it’s all too easy to forget to do it, but you should schedule it in.  Maybe monthly?
  2. Make sure that your tyres have the correct pressure.  Each car has its own preferred pressure. You’ll find this helpfully stamped somewhere around the car – under the fuel flap, on a plate in the driver’s door or in the vehicle handbook.  This may need to be adjusted if you’re doing a lot of towing or have a heavy load to carry (or if you do a lot of high speeds – but if you’re a racing driver, you’ll have a crew that helps you in this department).  Don’t guess – use a proper gauge.  A lot of air pumps have good gauges on the hose thingummy.
  3. wear_patterns
  4. Rotate your tyres regularly.  Different tyres wear at different speeds depending on your drivetrain, your suspension and where the loads are in your car.  Rotating means that your tyres wear out more or less evenly and the ones that really do a lot of work will have plenty of tread.  They day that every 10,000 kms is a good schedule for rotating tyres.  Exactly how you rotate your tyres will depend (again) on your drivetrain and whether or not your spare tyre is a space-saver or a full-sized one.
  5. Keep up the wheel alignments – twice a year is recommended.  This also helps the tyres to wear evenly, so you know that if you’ve got 2 mm on one part of the tyre, it’s going to be like that on all the other parts of the tyre, too.

Tyres are not something I’m ever going to neglect.  Not since the time I was in a crash that happened because the car lost traction thanks to bald tyres.  The driver wasn’t hurt and neither was I, but the car was written off.  You don’t forget a lesson like that in a hurry.

Safe and happy driving,