How to Make your Cars Tires last Longer
An automotive tire is an amazing device, really. Tire development advanced greatly following WWII both in performance and durability. During the 1950’s and 1960’s it was not unusual to find oneself replacing the tires every 8,000 to 10,000 miles. Over the last 50 years tires have advanced from bias ply through belted ply to the present day radial ply tire. With this progress came better compounds and a tripling or quadrupling of tire mileage. As long as the driver/owner takes care of them, that is.
The causes of early tire replacement are discussed herein with most egregious tire offenses listed first. Avoiding these offenses will go a long way towards extending tire life:
Incorrect wheel alignment is the quickest way to ruin a tire. Wheel alignment is most commonly considered a “front end” issue although there are some cars with independent rear suspension that need to be aligned as well. Incorrect wheel alignment accelerates tire wear by overloading an area of the tire or actually scrubbing rubber off the tire tread. Incorrect wheel alignment affects vehicle handling and this condition will also impact fuel mileage.
Under-inflation is another source of tire abuse. The damage is related to how much the tire has been underinflated. As the tire moves down the road it flexes where the tire contacts the pavement. This flexing creates heat which in extreme cases damages the casing and can cause catastrophic failure. Under-inflation causes the section of the tire tread nearest the inner and outer sidewall to carry more of the load. An underinflated tire will exhibit excessive wear on the inside and outside tread area with less wear in the middle section. The “contact” patch, that area of the tire tread in contact with the pavement, is reduced and therefor traction is reduced. Further, the sidewalls flex more under side load, such as when a steering input is applied. This is felt by the driver as less precise steering control.
Over-inflation, something advocated by those seeking fuel mileage improvement, is also damaging to the tire and hinders vehicle control. In this case the center section of the tire tread carries more of the load. An overinflated tire will exhibit greater wear in the center of the tread and less wear near the inner and outer side walls. Those seeking improved fuel mileage are attempting to reduce rolling friction by increasing inflation pressure, which reduces the size of the contact patch. The power demand created by rolling friction is directly related to vehicle speed and is very minor compared to wind resistance drag. The cost of tire replacement resulting from over-inflation far outpaces the miniscule fuel cost savings, if any.
Front wheel drive vehicles place a unique demand on tires. Unlike a conventional rear wheel drive vehicle, which uses the front wheels to steer and rear wheels to drive, the front wheels on a front wheel drive vehicle must perform both tasks. It is not uncommon to find the front tires on a front wheel drive vehicle wearing twice as fast as the rear tires even if the driver is taking proper care of them. Tire rotation will help to extend tire life and is more important in this case than with a rear wheel drive vehicle.
A final comment on tire size would seem appropriate at the end of this article and in light of a common practice to add custom wheels with much larger diameter tires. One item to be understood is the term “unsprung weight”. The tire and wheel assembly is separated from the vehicle via the suspension. One of the major purposes of the suspension is to keep the tire in contact with the road when going over bumps and ruts, and keep the tire in proper alignment with the road surface in curves, braking and acceleration. The wheel/tire assembly is unsprung weight and the springs and shocks are engineered to control that weight. Larger tire/wheel combinations are much heavier than those originally intended for the vehicle and the suspension cannot properly control the inertia incumbent to the movement of the heavier assembly. The result is a potential for momentary loss of tire to pavement contact and a reduction in vehicle control.
The vehicle manufacturer locates a panel on the vehicle’s door jamb with tire size and inflation data, and this information is included in the owner’s manual. This information is the result of design studies and actual vehicle performance testing. The driver ignoring this data is putting his pocketbook, or life, in jeopardy.
