Of all the things that will hurt your tow vehicle's fuel efficiency, running on underinflated tires is the most common problem—and the most easily fixed.
In a recent study, the National Highway Transportation Safety Administration found that 40 percent of light trucks and 27 percent of cars have at least one tire that is underinflated by 8 psi, or more.
From a safety standpoint, tires underinflated by as little as three pounds adversely affect a vehicle's handling, steering and braking. But where it hurts first is in the wallet. For every 1 psi that all four tires are underinflated, there's a 0.4 percent drop in fuel economy. Consequently, driving on tires underinflated by 8 psi cuts your gas mileage by more than 3 percent.
It may not sound like much, but it adds up. If you drive 25,000 miles per year in a vehicle that averages 15 mpg, and assuming gas is $2.50 per gallon, that 3 percent turns into an extra $145 at the pump each year.
And that doesn't even take into account the additional money you'll spend on replacing tires that wear out too quickly. Underinflation causes the edges to wear faster than the center of the tread face, and the constant flexing tends to overheat the tires, further shortening their useful life.
The same holds true for trailer tires. Nothing accelerates tire problems faster on a boat trailer than underinflation. Maintaining proper tire pressure is an easy way to keep cash in your pocket.