Tyre maintenance – how to keep them rolling longer

Saturday mechanic
Date:30 June 2008 Tags:

Degree of difficulty – Easy

Any kind of tyre failure – even a simple flat – is a huge hassle. Most problems are caused by under-inflation, overloading your vehicle, or damage from things such as debris, kerbs or potholes. Here are some things you can do to avoid such problems.

Pre-flight inspection
At least once a month, check your tyre pressure, and do it at least 6 hours after the vehicle was last driven. Don’t try to “eyeball” the pressure – you can’t see the difference between a properly inflated tyre and one that’s even 0,7 bar under. Some tyres always look under-inflated. Some have stiffer sidewalls and always look normally inflated.

Read the tyre specifications, which are in the owner’s manual and usually on the driver’s front doorjamb or the matching surface on the pillar. These specs are often lower than the maximum pressure allowed on the tyre’s sidewall, but they’re based on each particular vehicle and its rated load, not what the tyres are physically capable of withstanding.

Although tyre pressure specifications usually peak at 2,2 to 2,5 bar, buy a tyre pressure gauge that reads to at least 4 bar. That’s a typical pressure specification for a compact spare. (And don’t forget to check the pressure in the spare periodically, too.)

Go for the max
If the vehicle manufacturer specifies a pressure range, such as a minimum and a maximum, always use the maximum. The higher the pressure, the greater the loadcarrying capacity of the tyre, the more stable the vehicle’s handling will be, and the cooler the tyre will run at speed.

A normal tyre leaks a small amount of air. In addition, as ambient temperatures drop with the change of seasons, so does the air pressure in your tyres. Although higher tyre pressures stiffen the ride somewhat, it’s a small price to pay for the extra safety and the ability of the vehicle to accommodate greater loads. Maintaining proper tyre pressure also improves fuel economy, although not by much. Caution: over-inflation increases centre tread wear.

Inspecting tyres
Wheel alignment also plays an important role in tyre performance. If the wheels are mis-aligned, they don’t roll true down the road. The side slippage produces friction, which raises tyre temperatures and not only increases tread wear, but also causes the wear to be uneven.

The treads should be deepest at midpoint – at least 3 mm thick. That’s 1,6 mm above the tread bars that are the official “replace them” indicators. The wear pattern should be relatively even at each side, although it might be somewhat greater in the middle. Tread wear that is “feathered” – worn to a sharp edge at one or both sides – or much greater on one side is a sign of misalignment.

If you see cup-like wear in the treads, typically along one side, the possible causes are out-of-balance wheels, wornout shocks or struts, and loose suspension components. The classic sign of unbalanced wheels is high-speed (80 km/h and up) vibration, and it usually surfaces before cup-like wear becomes noticeable.

Suspension problems usually produce shake at lower speeds. Tyres with unevenly worn treads should be replaced, unless the problem is caught early and there’s plenty of tread depth left. In that case, the tyres could provide a moderate amount of life on the rear wheels, particularly on a front-drive car. If you have an all-wheel drive that you push pretty hard, however, invest in an entire set of new tyres.

Look for any cuts on the surface of the tyre that expose the steel belt or fabric cord. This is grounds for immediate replacement.

Wheel balancing
Get your wheels balanced with a highspeed spin balancer, not a bubble balancer. Make sure the workshop has weights designed for your wheels. It takes at least a half-dozen differently shaped weights to fit properly on the rims of all the popular wheels. There are several so-called universal weights, but they may not fit your rim, and could pop off or cause rim damage.

Sidewall check
Use a tyre and wheel-cleaning product to give you a clear look at both the tyres and wheels. You should then be able to find cracks in the wheel, damage to the tyre sidewalls that goes beyond surface nicks, and damage to the bead area that could be responsible for pressure leakage.

Tyre rotation
This subject is not so simple. Cost of rotation versus longer tyre life is not a precise equation. Unless the lug nuts are tightened to specifi cations in three even stages, using a criss-cross pattern, the rotors may become warped, which adds to maintenance costs.

If you let the mileage stretch out a bit, such as to 16 000 km or more, tyres may develop almost imperceptible wear patterns that will affect ride when they’re moved to a new position on the car. If you can’t rotate the tyres often, you may be better off leaving them in place and accepting the somewhat shorter tread life.

Some tyre treads are directional. They should spin in only one direction and should not be cross-rotated. How can you tell if you have this type of tyre? Look for a directional arrow on the sidewall.

Careful tyre maintenance may extend the lifespan of your tyres – and will guard your own.