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lou's garage

New tires go on the rear axle.

When purchasing two tires only, they need to be installed on the rear axle. This practice has been around for several years, but I still receive resistance when trying to convince some customers that this is the way it’s supposed to be.

Let me explain. Part of the answer lies in understanding understeer versus oversteer. When you turn your steering wheel and the vehicle fails to turn as much as you expect it to, this is known as understeer, because the vehicle keeps traveling in a forward, straight-ahead orientation. Alternatively, when you turn your steering wheel and the vehicle turns more, or sharper than you expect it to, this is known as oversteer.

Now assume for a moment that you have a vehicle with two brand new tires and two 50-per-cent worn tires. Since the new tires have deeper tread and are better able to clear water and snow, there will be an imbalance of water evacuation between new and old. This imbalance may cause hydroplaning of the two worn tires, though only in wet conditions.

Now, back to the oversteer versus understeer question. If you install new tires on the front, the superior water evacuation and traction will cause the vehicle to have a tendency to oversteer. If the new tires are installed on the rear of the vehicle, it will typically understeer. For the average driver, a vehicle that understeers is far easier to correct than one that oversteers. Remember, a vehicle that understeers will generally keep going in a forward direction, while one that oversteers is more likely to spin out.

I do understand that partially worn tires installed on the front axle of a front-wheel-drive vehicle is counter-productive to tread life, as they will be stuck there, unable to be rotated from axle to axle. Old-school thinkers will point this out with vigour. However, this thinking is now dated, as safety trumps inconsistent tire wear.

There is no specific law stating that new tires have to be placed on the rear axle. But by not adhering to basic tire-industry guidelines, your vehicle service provider will put themselves in a position of liability should an accident occur. Essentially, any wet-weather crash that results in bodily harm may lead to court proceedings that will subsequently involve tire-condition analysis. If there is significant tread-wear difference from front to rear and they are not in the industry-recommended positions, a legal team will go looking for your professional tire-shop service records dealing with tire rotation and/or the sale of two tires only.

As a DIYer, you are free to do whatever you wish. I don’t recommend it, but doing so places you in a position of liability. Very few shops will allow themselves to be talked into placing two new tires on the front axle of a front-wheel-drive car. Don’t fight them, just let them do as they are supposed to and then purchase two more new tires as soon as possible so that you can rotate your tires properly. We won’t remind you that you’re in this position in the first place because you didn’t properly rotate your tires, I promise.


Your automotive questions, answered

Hi, Lou.

I drove over a medium-to-large piece of ice in my parking lot. Can I damage the undercarriage? I also put my car in drive immediately after starting it, not waiting a few minutes. But the dashboard lit up like a Christmas tree when I restarted it. It’s working fine now. There’s 15,900 kilometers on it, and I’ve done two oil changes already. Thanks!

Tor R

While I doubt that the actual metal undercarriage would suffer any damage, there is a reasonable chance that a sensor, wiring or plastic under-car shielding could have been harmed. The fact that warning lights were illuminated would support this. Considering the vehicle settled down and is working fine now suggests that everything is okay, but I would still want to have it inspected at your next oil change.

I store my 2015 BMW 228 Xi Cabriolet in my unheated garage from mid-October to the start of May. I change the oil and filter every October, using 5W30 Synthetic oil. The average kms per year is approximately 2,600. A BMW Battery Maintainer keeps the battery at close to 95-per-cent power. Do I need to change both the oil and filter in the spring? I have received different recommendations from dealers.

Thanks,

Bob, Blue Mountain, Ont.

My wife drives a 2007 Honda Fit and only drives, on average, 3,000 km per year at most. With Honda’s schedule of oil changes due every 10,000 km, should I still get an oil change each year or simply follow that mileage schedule?

Thanks for any info.

Paul O, Kingston

I just changed the oil in my 2004 Toyota Tundra V8. I do it myself usually at 6 months or 8,000 km, if I get there. Now that I am retired, I really don’t drive it much except when towing my race car to the drag strip. This year, I changed the oil on Feb. 24th at 137,042 km, and today it was at 139,719 km – less than 3,000 more. Am I wasting my money? Is it OK to go one year between oil changes, as long as the milage is less than the recommended? I run conventional 5W30 oil.

Thanks,

Tony B

Since these are essentially all the same inquiry, I can clear three questions in one answer. Low-yearly-kilometer-driven vehicles don’t require an oil change every six months. Once per year is fine using a full synthetic oil and premium oil filter. The only time this answer would differ is when your vehicle is still under warranty. Those vehicles have to observe the guidelines set forth in their maintenance schedules as provided by the vehicle manufacturer. Tony with the Tundra, switch to synthetic and leave it to yearly, unless you start towing more frequently.

Changing it in the fall versus the spring might be the only point that will get people debating. Some experts state that the broken-down contaminated oil will cause issues over the winter. Alternatively, others state the moisture buildup over the winter months will cause problems. For the record, I change the oil and filter in my classic Porsche in the spring, before my driving season starts. You will see differing opinions on timing; however, the more important point is ensuring it is done once per year.

Lou Trottier is owner-operator of All About Imports in Mississauga. Have a question about maintenance and repair? E-mail globedrive@globeandmail.com, placing “Lou’s Garage” in the subject line.

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