Put tires at top of car safe driving list
With summer fully upon us, it’s already a little late to get our vehicles ready for the hot dry and rough weather and conditions ahead. Getting this accomplished before you need it is the way to go.
Some people call this winterizing and remember about anti-freeze, wiper fluid, water-grabbing gas additives and wiper blades.
While some climates aren’t as severe during the winter, these are all good things to take care of no matter where you call home, and at the top of the list is tires.
Most of us use all-season tires, so all we need to do is check the condition, age and pressure. The condition is the hard part tread depth, road damage and sidewall cracks are some of the easy things to miss. Damage can be hard to find, so spend some time looking closely.
Don’t tolerate sidewall cracks. Sometimes called “dry rot,” and these deterioration patterns suggest the rubber is nearing the end of its lifespan. Trying to stretch this can leave you stranded or much worse, so you should have a professional inspect them. They know from experience there’s just no way to predict failure when these cracks start appearing.
If your tires are more than 5 years old, it’s time to think about replacing them. Every tire has a “birthday” stamped on the side, and the Department of Transportation requires tire manufacturers to follow a standard marking scheme. Of course, the tire’s birthday is in code. The “magic decoder ring,” which displays a tire’s birthday, is available on the DOT website.
The “US DOT Tire Identification Number” is stamped on the sidewall near the rim. On some tires, it’s hidden on the axle side, more commonly on raised white lettered tires. You might have to scoot around under the car a bit to find it. Once you find the code, it contains the tire’s birthday. The last four-digits of the DOT number reveal the week and year the tire came out of the factory, so 2809 would be the 28th week of 2009.
Tread depth is easy to remember and all you have to do is use a penny. Turn it upside down and if you can see the top of Lincolns head, YOU DON’T HAVE ENOUGH TREAD!
The only tire pressure you need to know is the one printed on the vehicle data plate. Most of these are on the driver’s side door jam. It displays the manufacturer’s recommended tire pressure, as their judgment of the best compromise between traction, handling, noise, wear, etc. They tune the suspension components around this number and have carefully determined how the tread contacts the road, called the contact patch, at that pressure. Any deviation makes you the test pilot.
The factory recommended pressure is a “cold” pressure. The engineers know the pressure will rise with heat, and if you are using the same size and brand the car was born with, no worries. But if you change the tires, you need to make sure the maximum allowable pressure for that tire (also printed on the tire sidewall) gives you some headroom as the tire heats up.
The only way to know how much margin you have is to stop and take a reading on a hot day after some time at highway speeds.
That temperature sensitivity (about one psi for every 10 degrees Fahrenheit) means you have to adjust the tire pressure as the seasons change, typically in fall and spring. Now that summer is behind us, many people are probably seeing some tire-pressure warning lights if their vehicle has a tire pressure monitoring system.
If you filled your tires when it was 95 degrees outside last July, when the temps dip into the 30s, you could be almost 10 psi low. It’s best to check first thing in the morning, and in the shade. That will give you a true “cold” reading.
With gas prices still on the rise, there’s a temptation to “add a little extra” with thoughts of decreasing rolling resistance and increasing gas mileage. The extra air consumes your margin, and causes the contact patch to change shape. It mucks with the handling, wet traction and braking effectiveness, plus it makes the center of the tires wear out faster than the edges.
There are tons of misinformation on the claimed benefits of using nitrogen in vehicle tires. It would take pages to dispute all the rhetoric out there on this subject, so look at the big ones. First, remember that air is around 80 percent nitrogen to begin with, so we aren’t talking huge differences to start out with.
There are claims that nitrogen is a good deal because it leaks out more slowly (backed up by pointing out nitrogen’s slightly larger molecular size). A consumer magazine took on this myth and found out it’s actually true, but on the order of one or two psi a year. Since you have to adjust your tire pressure at least twice a year anyway, that difference isn’t going to save you a trip to the air pump.
spare tire serves as a backup in case your car has a flat. Vehicles typically carry a spare tire mounted on a rim, to be used in the event of flat tire or flat tire. Many spare tires for modern cars are smaller than normal tires to save on trunk space, gas mileage, weight and cost and should not be driven far before replacement with a full-size tire. Jacks and for emergency replacement of a flat tire with a spare tire are included with a new car. Hand or foot pumps for filling a tire with air are available. Cans of pressurized “gas” can be bought separately for a convenient emergency refill.
Spare tires come in a variety of sizes and versions. Many cars are equipped with temporary spare tires and wheels, which are noticeably different from regular tires and wheels. Some require higher inflation pressure, or the use of a pressurized canister to inflate the tire. The only type of spare tire that can be used without such restrictions is a conventional, full-sized spare that is the same as the other tires on the vehicle.
The Folding Spare- must be inflated with an air canister prior to mounting.
The Compact Spare- smaller and narrower than the other wheels on the vehicle.
The Lightweight Spare- the same diameter as the other tires on the vehicle but thinner.
These tires are:
- labeled “temporary” spares because of their weight-saving construction.
- are intended for emergency use only and not for sustained or high speed driving.
- not to exceed 50 mph nor to travel further than 50 miles.
Maintenance Tips and Suggestions
Tire Air Pressure – Check the air pressure in your spare tire whenever you check tire pressure to be sure your spare is in top condition in the event of a flat tire.
Know How to Change Your Tire – Become familiar with the equipment needed for changing a tire and be sure essential tire-changing tools are in good repair and where they should be. Practice changing a tire. Always check your owner’s manual and the tire sidewall for instructions on proper use of a temporary spare.
- Locate the jack, handle and lug wrench.
- Know where the jack contacts the vehicle when raising it.
- Locate the key for wheel locks.
- Know how to access the spare tire.
A functional spare that is in good condition is a comfort. By avoiding the following pitfalls, you can be assured that your spare tire is in good form.
- Under inflation – If your spare is low, it may shred on the way home or to the service facility. The distance you can travel before this happens is directly related to the tire’s inflation level. Check the pressure of the spare, as well as the other four tires every month.
- Dry Rotting – Tires deteriorate with age. Tires do have a shelf life. After a period of time, they may begin to develop small cracks in the sidewall.
- Inaccessibility – The leading reason spare tires fall victim to under inflation and dry rotting is inaccessibility. Clear out the trunk and check the spare or take your car to a shop and let an auto tech check your spare.
Spare Tire Safety
- Most space saving spares are limited to 50 miles and 50 m.p.h. Replace a temporary spare with a full-size tire as soon as possible.
- Keep your compact spare and its wheel together and do not use them on another car.
- Do not use tire chains on a space saving spare. They won’t fit and will damage the car as well as the chains.
- Do not drive through a car wash that pulls the car along guide rails with a spare on your car. The spare can get caught on the rail and damage the tire, wheel and very possibly other parts of your car.
The bottom line is keeping up with the tire pressure is probably the single most important user-safety and gas-savings task you can accomplish, and it does take some intervention as the seasons change. However, this is not the place to get creative. Follow the factory numbers, check it often and stay safe.
Safety Alerts are a publication of the information from various sources to share with the community. The information contained in this newsletter has been obtained from sources believed to be reliable, and the editors have exercised reasonable care to assure its accuracy. However, Ken does not guarantee that the contents of this publication are correct. We welcome topics of interest from our readers. Material may be rewritten to conform to newsletter space. Material should be addressed to the Ken Oswald, Safety Manager, 583 US 70, Clovis NM 88101.