People’s eyes glaze over when you try to explain to them why they have to keep a matched set of tires on their vehicles. They seem to suspect that the salesman is just trying to up-sell them from the one retread they requested, to 4 top of the line, brand new, hideously expensive rubber doughnuts. They refuse to listen to the salesman’s safety-oriented suggestions about proper inflation. I know that this is a common human experience.

Right Tires Contribute to Proper Manoeuvrability and Reliability of Motor Vehicles, Photo by J. Star, Flickr

My Dad ran a tire shop, and he went to his grave a broken man because he knew that his customers greeted his tire suggestions with disdain. They could not believe that tire safety was a crucially important topic. They needed a comparison with a commonplace situation where the truth of the salesman’s words can ring true. If they can relate the use of tires to something familiar, they can grasp the tire salesman’s arguments, self serving as they may seem. That’s why I always explain safe tire requirements by comparing their performance to what happens when you outfit your pet elephant with inflatable rubber-soled shoes.

Jumbo represents the weight of your car. His inflatable rubber shoes represent your tires. If you put three brand new, correctly inflated rubber shoes and one old thin, bald, half empty shoe on Jumbo, how do you think he’d walk? What would the problem be? You can easily imagine that the inferior shoe would impede his progress on slippery slopes, or icy ground. He’d have no traction on this poorly equipped leg. The bad foot would slide out from under him, causing him to lose control, falling around, and sliding about. You understand that this would happen to your elephant. Why do you insist on trying to make this scenario have a good outcome when applying it to your car? You know the cure too!

All the tires should be equally worn for proper traction. Conversely, if you put one good shoe on Jumbo, and 3 crappy ones, you instantly understand that this wouldn’t work either. In order to have even distribution of traction ability, the car needs 4 good tires. But sometimes financial constrictions dictate that a person only buy two tires. Once again, the elephant analogy will help people decide where the new tires must be placed.

Jumbo is a front wheel drive animal. If he’s wearing two worn old shoes on the front two legs, and two new shoes on the rear feet, how do you think Jumbo will handle wet, muddy or icy patches? Yes, his front feet will not have the strong traction that the back ones will have. This will result in his front legs buckling when pushed from behind. The frontal weakness will have Jumbo all off kilter. However, if you put the good shoes on the front feet, he’ll clump along much more steadily. A car is also much more efficient if the two new tires are installed on the drive axle. They should go on the back wheels of a rear-drive car.

Unfortunately, this analogy won’t work when proper tire inflation is being discussed. We’ve all put new shoes on our elephants, but have we pumped him full of air? Tire shop owners are currently pushing the idea of filling tires with nitrogen. They cite better fuel efficiency and longer tire life as reasons to use this gas. And another thing! Regular air loses about 1.5 psi in a month, whereas nitrogen holds the pressure better. They say that it takes nitrogen 6 months to lose 1.5 psi.

I suppose that the scientists among us could conduct their own experiments with balloons and regular air versus nitrogen. But my interests lie elsewhere. I’m off to check Jumbo’s footwear for signs of wear and tear. After all, I wouldn’t want him to be slipping and sliding when he goes out with his friends. Elephants can cause big pile-ups if not properly shod! Just like cars.