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Tire Maintenance

Tires are the most amazing part of each car, as their small surface contact area with the ground, each the size of a postcard, belie their tremendous effect on the car’s comfort and performance. In fact, to state that the tires are the most important part of each vehicle would not be entirely false. Therefore, the changing of tires is seen by some owners as the simplest method of upgrading the performance of their cars. Some sceptics might ask on the need to change the tires that come factory equipped, as the car makers would presumably know best. The car makers do know best, but their decision may have been a compromise between performance, noise, abrasion resistance, and comfort. Factory tires would thus be like jacks of all trades, and not the stellar performer enthusiasts are looking for.

The benefit of upsizing your tires:

• Improved response to direction changes
• Greater contact area with the ground
• Increased traction
• Greater overall control and handling
• A sleeker and more modern appearance

Having understood how much the tires affect the performance of the vehicle, we will now look into the various options of upgrades an owner has. The improvement in performance can take on one of two aspects.

Tire Model Upgrade
Pricier tires usually feature the usage of improved materials; sporting better aesthetically designed tread lines, lesser road noise, and improved drivability on water and grip on roads.

Tire Specification upgrade
Another method of upgrading is the purchase of bigger wheels and tires, within the safety limits set by the auto makers. The primary goal of most people who engage in this upgrade would be for the aesthetics of the car, with improved traction, safety and handling being complementary benefits. These are nonetheless tangible benefits so this method kills two birds with one stone!

From the above simple analysis, readers may be tempted to think, isn’t the second upgrade a better option with all the improvements of the first option, as well as improving the profile of the car? While this may seem that way on the surface, the tradeoffs for bigger wheels would be an increased body weight, and greater traction due to their increased width, both having an adverse result on the vehicle’s acceleration (another aspect of performance). The second option is also more expensive, as more and better materials are required in the production of bigger wheels and wider tires.

Therefore, there are some considerations to be made before choosing which option is best for you:

• Are you really dissatisfied with the specifications of your current tires?
• Are you looking to just improve one or two qualities? Noise, drivability in water, or traction?
• Is it more feasible to get a package deal upgrade, both wheels and tires?
• Is your vehicle able to maximize the performance gains of the bigger wheels?

New vehicle owners should not rush to upgrade their factory wheels, as the new tires that came with the car represent an irretrievable sunk cost. Instead, consideration should be made on whether you can accept the factory tires’ performance in the interim. Upgrading the tires can be fully explored when the tires need replacing.

One should consider the vehicle’s horsepower (hp) before deciding on upgrading the tires. If the hp is low, it will not improve performance by enlarging the wheel size. For example, a great majority of cars in Malaysia fall into the 1.3 to 1.6 litre passenger vehicle category. Most cars in this category weigh 1 to 1.2 tons and make between 115 to 135 hp, and use 185/60R14 tires. In these cases, some performance gains may be actualized if the tires were changed to 185/65R14, or if the width was reduced to 175mm. However, most owners choose instead to change to 195/50R15 or even 195/55R15, which only serves to increase weight and subsequently, fuel consumption.

Conversely, if your vehicle’s hp is above 200, changing the tire’s size and width may serve to improve handling due to the increased traction.

After you have decided to upgrade your tires, you should do some research. What the best tires within your budget are, what the leading brands are, and which tread designs you prefer. Generally, the heavier the tires, the more beautiful and deeper the tread designs, thereby increasing traction.

To a car owner, knowing he biggest wheel size that can fit into a vehicle is very important. There is a simple rule, which is the upgraded wheel’s diameter should not be larger than 3% of the original. For example, if we take the 185/60R14 specification as an example, with the original diameter size as follows:

Wheel diameter: 14 inches, 14 inch x 2.54 cm = 35.56 cm
Sidewall: 60% of the tire’s surface, 18.5 cm x 0.6 = 11.1 cm

But as each wheel has two sidewalls, the sidewalls have to be multiplied by 2,
Sidewall: 11.1 cm x 2 = 22.2 cm
Diameter: 35.56 cm + 22.2 cm = 57.76 cm

Is it possible to upgrade to a 195/50R15 tire?
Wheel diameter: 15 inches, 15 inch x 2.54 cm = 38.1 cm
Sidewall: 50% of the tire’s surface, 19.5 cm x 0.5 = 9.75 cm

As before, as each wheel has two sidewalls, the sidewalls have to be multiplied by 2
Sidewall: 9.75 cm x 2 = 19.5 cm
Diameter: 38.1 cm + 19.5 cm = 57.6 cm

Compared with the 185/60R14 specification tire’s diameter of 57.76 cm, the difference is only 0.3%, which is well within the allocated range.

But what if we just increase the tire surface without changing the thickness of the sidewall that is using a 195%60R14 tire?
Wheel diameter: 14 inches, 14 inch x 2.54 cm = 35.56 cm
Sidewall: 60% of the tire’s surface, 18.5 cm x 0.6 = 11.7 cm again x 2 = 23.4 cm
Diameter: 35.56 cm + 23.4 cm = 58.96 cm

Compared with the 185/60R14 specification tire’s diameter of 57.76 cm, the difference is now 2%, which is basically still within the allocated range, but because the diameter has changed in a big way, the entire tire circumference has also been changed, rendering the speedometer inaccurate. More importantly, the increased wheel size may cause the wheel to hit the inner wheel wall of the vehicle when the wheel is turned to its fullest. In serious circumstances, it will cause uneven wear and tear for the tire.

What the “Plus 1″ and “Plus 2″ mean in the picture below.

“Plus 1″ means, if the tire’s thickness is reduced from 70 to 60, the wheel size has to be larger by an inch, to ensure the wheel circumference is the same.

“Plus 2″ means, if the tire’s thickness is reduced from 70 to 50, the wheel size has to be larger by 2 inches.