Bridgestone Commercial Truck Tires

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Traditionally, tire cost per mile was a simple calculation of total tire cost, divided by total number of miles. The only question was what to include in "total tire cost." Basically, the result you got was the tire's "wear cost" per mile.

With tires advertised as "fuel efficient," some folks began evaluating tires on the basis of the amount of fuel they hoped to save. Sometimes, they almost ignored wear costs, focusing almost exclusively on fuel.

Because both methods, taken alone, can be pretty inaccurate, there's now a new way to look at both a tire's "wear cost" and its "fuel cost." We call it "Tire Life Cycle Cost," and your Bridgestone representative has a computer program to help you calculate it - and compare it - for various tire choices.

What is "Tire Life Cycle Cost"?
It's a new way to compare tire costs over original tread life, taking into account both the number of miles the tire remains in service, as well as how much fuel the tire consumes.

But tires don't consume fuel!
Not literally. But a certain amount of the energy in fuel is used to roll the tires down the road. This energy overcomes tire rolling resistance.
So, you can say that in a sense, your tires do "consume" a certain amount of fuel.

Bridgestone's new Tire Life Cycle Cost program combines data on both wear costs and fuel costs to produce a more realistic comparison of different tires.

How do you measure that?
There are well-accepted procedures, established by the Society of Automotive Engineers, to measure rolling resistance, and therefore, the fuel consumption you can attribute to your tires. The trick is that tires don't always contribute the same amount to truck fuel consumption.

Why is that?
First of all, tire rolling resistance changes with load, speed, inflation, etc. That should come as no surprise. What might be surprising is that rolling resistance changes with wear. In fact, it changes constantly. In general, tire fuel economy is worst when tires are new, gets better as they wear, and is best right before you remove them for retreading.

For all tires?
Even fuel-efficient tires? We haven't found any exceptions yet. And here's the problem: most claims of tire fuel efficiency are made regarding tires that are practically brand-new.
Yet, as they approach wearout, the fuel efficiency of most tires becomes quite similar. So, you can't make good judgments about tire fuel efficiency based on new tire testing alone.

The Tire Life Cycle Cost program lets you compare different tires to determine which is more likely to produce a lower overall cost per mile, when both wear rates and fuel economy are considered.

How do you do it?
Bridgestone engineers worked with an independent lab, Standard Testing Laboratories, Inc., to measure tire rolling resistance at different wear levels.
Then, knowing fuel consumption at those different wear levels, they created a mathematical model to predict a tire's fuel consumption over its entire original tread life.
That's why we use the term "Tire Life Cycle Cost."

What about the wear factor?
That was added to the model. The result is a sophisticated new computer program that allows your Bridgestone representative to compare different tires, different vehicle configurations, even different fuel prices.

Can we plug in our own data?
You can provide your Bridgestone representative with the price you pay for tires, what you pay for mounting, balancing, etc., what your used casings are worth, your fuel price, your normal loads, tire mileages and vehicle configurations.

Testing shows that as tires wear, their fuel efficiency changes constantly - and near wearout - differences between tires tend to disappear.

The program also calculates the total annual savings you can expect, based on your tire selection.

What tires are included?
The program has data for many popular tires by Bridgestone and other premium tire manufacturers. Not every tire brand, model and size is included, though more will be added over time, but we think you'll find it's a good selection.

Does the program include retreads?
Not at this time. As you can imagine, performing the necessary tests on rolling resistance and fuel consumption, at different wear levels, is expensive and time-consuming. And, imagine how complex it would be for retreads. You'd have to test different combinations of casings and treads, mold-cure and pre-cure - an almost endless number of combinations.

What will the results tell us?
You'll be able to compare tire cost per mile in a more meaningful way. You'll be able to see whether a fuel- efficient tire is really a good choice by comparison to a tire that provides long original tread life. You'll be able to see the effect of shifting fuel prices, different loads, different vehicle configurations, etc.

Will the numbers tell us what we can save?
You'll be able to make relative comparisons. The program can't take into consideration things like driver habits, idle times, terrain, traffic, weather and so on. All it can do is give you a better idea of how much different tire choices might cost you.

How do we get real results?
The same way you always have - by trying different things and keeping good records. What we're trying to do with this program is reduce the number of things you'll have to try.

Can we get a copy of this program for ourselves?
Because of the program's complexity, and because of the training, hardware and software needed to run it, only Bridgestone representatives can demonstrate it for you. The good news is that they'll be happy to do it.

Editor's Note: To help you conserve fuel, Bridgestone offers a free, 56-page guide to truck fuel economy, along with a video on what drivers can do to save fuel. To get your free copies, just mark the box on the business reply card enclosed in this issue.

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