Look among the most important insights a fleet manager must have for success and you will find a keen awareness of the difference between the goals of a customer and that of leaderships. Fleet managers are in a constant state of unsteadiness as they endeavor to walk the tightrope of production and expense. Whenever possible I try to find one good “hot button” everyone can agree on and promote a new program that is mutually beneficial, this gets all parties working together and builds a shared sense of purpose.
Recently I have promoted healthy tire pressure and uniform tread thickness on dual wheel axles. Most high mileage over the road fleets study the math and science of tire wear to the limits of the human mind but the concept is largely overlooked in the municipal fleet. This is one of those issues I thought I already knew all about but when I really looked into it I found a golden opportunity to add life to tires, save fuel and make the operators happy. I jumped at the chance to have everyone singing from the same songbook for a change.
************If you can stand to miss out on all the boring math skip to the ************* Line.
ABANDON ALL HOPE YE WHO ENTER HERE
Ok for all the folks still reading… Hello fellow fleet geeks… I will try to make this as painless as possible. First we are talking about predominantly 22.5 inch tires commonly found on class 6, 7 and 8 trucks with a dual wheel axle (actually 4 tires per axle). A common 11R 22.5 drive tire will have a circumference of; say, 128.42” when inflated to 100 lbs. If a companion tire (one tire bolted to another) is even 10 lbs under inflation it will have about 127.17” in circumference this means the correctly inflated tire will drag 52.98 feet for every mile driven due to the smaller tire spinning faster. A little more math; if tire expectancy is even as low as 20k miles we would have to multiply that 52.98 feet by 20,000 and then divide by 5280.
52.98 times 20,000 divided by 5280 equals a little over 200 miles a tire has dragged all because of 10psi in tire pressure and/or 1.3 inches difference in circumference Go ahead multiply 200 miles by every dual axle in your fleet; (com’on I dare ya)’… SHOCKING!!!!!!
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So; blah, blah, blah dragging big ole’ tires around is bad.
By admitting the fact that we would never willfully drive a piece of equipment with a tire dragging; because of all the nasty effects there-in, we can now enforce why we would never leave the lot with unmatched or under inflated tires. So check inflation and check circumferences at every inspection and always replace tires in axle sets for optimal results. And a good time will be had by all (well; most, my apologies to the heavy truck tire guy)
