Maintenance

It is important that every vehicle has its 4 wheels correctly aligned. A vehicle is properly aligned when all suspension and steering components are sound and when the tire and wheel assemblies are running straight and true. In its most basic form, a wheel alignment consists of adjusting the angles of the vehicle's wheels, this to make sure that the wheels travel in relation to the geometric centreline of the vehicle. Each wheel has its own set of dynamics (camber, caster and toe) specified by the automobile manufacturer.

The most common symptoms of a car that is out of alignment are uneven or rapid tire wear and when the car is pulling or drifting away from a straight line. When you notice these kinds of problems on your car your wheels are most probably not properly aligned. In such a case Sava recommends to have your vehicle alignment checked by a specialist, who is using modern computer aided vehicle alignment equipment. Today many tire specialists and car dealers have such sophisticated equipment and offer vehicle alignment services.

The best type of wheel alignment is a four wheel alignment. For this type of alignment the technician will place an instrument on all four wheels and measure the vehicle dynamics on all four wheels. Today, many cars have adjustable rear alignment settings, but even for cars without adjustments in the rear, a four wheel alignment will allow the technician to identify any rear tracking problems and compensate them with adjustments to the front. The two wheel alignment, in which only the front wheels are aligned to the centreline, has become obsolete.

Out-of-balance tires cause a car to vibrate at certain speeds. This can lead to premature, irregular tire wear, as well as unnecessary wear to your vehicle's suspension. Tire balance should be checked at the first sign of a vibration. The best way to explain tire balancing is to begin to explain what a lack of balance is. When a tire is mounted onto the wheel, two slightly imperfect units are joined to form an assembly. The chances of this assembly having absolutely precise weight distribution about its radial and lateral centers are virtually impossible. Usually wheels can present two types of imbalance: Static Imbalance and Dynamic Imbalance.

Most assemblies have both types of imbalance, and require dynamic balancing to create even weight distribution. Static Imbalance: Occurs when there is a heavy or light spot in the tire. In this case the tire does not roll evenly and the tire and wheel undergo an up-and-down motion. Dynamic Imbalance: Occurs when there is unequal weight on one or both sides of the tire/wheel assembly's lateral centerline. Dynamic Imbalance can cause a side-to-side wobble or wheel shimmy. To balance the wheel, the technician mounts it on a balancing machine, which spins the wheel to locate the heavier parts of the assembly. The balancing system then directs a technician to place counter weights on the rim's surface to offset the imbalance.

Sava recommends you to check your tires inflation including the spare tire at least once a month with an accurate tire pressure gauge. With the right amount of air pressure, your tires wear longer, save fuel, enhance handling and prevent accidents. If you consider the liabilities of not maintaining the correct air pressure -- poor fuel mileage, loss of tire life, bad handling (perhaps even loss of control), and potential vehicle overloading -- then the need to routinely checking of your tire inflation will become clearer.

The correct air pressure may be found in your vehicle manual or on the tire sticker (attached to the vehicle door edge, doorpost, glove box door or fuel door). If you cannot find the air pressure information Sava advises you to contact a local tire dealer for assistance.

Many people believe that they can check air pressure just by looking at the tire and judging the sidewall appearance. However properly checking tire pressure requires an accurate air gauge. Note that air meters at service stations, can be grossly inaccurate due to exposure or abuse. The best way to check your tire pressure is to visit your nearest tire dealer. When checking your vehicle's tire pressure, make sure the tires are "cold". Cold air pressure means that the vehicle has not yet been driven (remember that driving on a tire increases its temperature and air pressure).

All passenger, light truck, and medium commercial tires have tread wear indicator bars moulded in the tread. These bars are located at the bottoms of the tread grooves in several locations around the tire. Their location is indicated in the shoulder area by little triangles. When a tire is worn to the point where any of them become visibly flush with the adjacent tread ribs, it is time to replace the tire. In other words, if the tire is worn to the point that the treadwear indicators are at the same height as the adjacent tread ribs, this means that the tire has only 1.6mm of tread depth left. You should replace your tires immediately as the performance of your tires is no longer optimal and last but not least, 1.6 mm is the legal minimum tread depth required by law.

The performance of a tire on wet roads decreases with the remaining tread depth. With a reduced tread depth the tire is not able to evacuate the same quantity of water as before and therefore the risk of aquaplaning increases. Moreover, the braking performance on wet roads is reduced. For that reason it is generally recommended to replace your summer tires when less then 3 mm profile depth is left. Our winter tires are equipped with special winter wear indicators. The locations of these winter wear indicators in the tread are indicated in the shoulder area with a snowflake. When the tire is worn to the point that the winter wear indicators are at the same height as the adjacent tread ribs the tire has only 4mm of tread left. It is generally recommended to replace winter tires with less than 4mm profile depth, to ensure optimum driving performance in winter conditions. If your tires wear off irregularly, this may be an indication your tires don't have the optimum tire pressure or that your car has some kind of chassis problem.

- If the tread is deeper on the edges than it is in the centre, the tire is possibly over-inflated. 
- If the tread is deeper in the centre than it is on the edges, the tire is possibly under-inflated.
- If the tread is deeper on one side than it is on the other, have your wheel alignment checked soon.

For further information on tire pressure or tire balancing, please take a look to the respective maintenance pages.

Rotating your tires periodically is an important part of tire maintenance. The main purpose of regularly rotating tires is to achieve more uniform wear for all tires on the vehicle. If no rotation period or pattern is to be found in your owner's documentation, rotate your tires at least every 8.000 to 10.000 km. However, rotate your tires earlier if irregular or uneven wear develops, and check with a qualified tire dealer or alignment shop to determine the cause of the wear problem. Remember that a hard impact such as hitting a pothole can cause misalignment, which then causes uneven tire wear.

On front wheel-drive cars, it is especially important to rotate your tires periodically because the front tires wear faster than the rear tires. Uneven tire profile depth, front to rear, will give you uneven braking and poor handling, especially in the rain. If you don't rotate the tires, you'll wind up replacing them two at the time, which means you'll always have uneven tread thickness. Replacing tires in a matched set of four will keep the handling and braking traction of the car balanced.

Pay attention if you have directional tires. Directional tires would remain on the same side of the vehicle and be rotated straight forward and straight back to avoid the tire to rotate in the wrong direction. To be sure if your tires are directional please check the tire sidewall for an arrow with the word "rotation" on the sidewall.

Also, some vehicles may have different sized tires or axle specific tread designs mounted on the front and rear axles, and these tires may have rotation restrictions.

If your tire has lost all or most of its pressure you should stop your car immediately and fit your spare tire. Therefore Sava suggests to regularly check the tire pressure of your spare tire as well so to make sure you can use it when you need it. Never continue driving on a flat tire as this will damage the tire structure. Once you have mounted your spare tire you should visit a specialised tire fitter to have your damaged tire checked whether it can be repaired. Note that only a specialist tire dealer can tell you if your tire can be repaired, as the tire must be removed from the wheel for a complete internal inspection to be sure it's not damaged. Flat tires that are run even for short distances are often damaged beyond repair.

Most punctures nail holes, or cuts up to 6mm in the tire tread can be repaired by trained personnel using industry-approved methods. Tires with tread punctures larger than 6mm, or any sidewall puncture should not be repaired. It is also recommended not to repair ultra high performance tires (tires with a speed rate W, Y or ZR). Please bear in mind that the final decision whether a tire can be repaired or not should only be taken by trained tire specialist.