AXLE RATIOS: LOW GEARS, HIGH GAINS

Choosing an optional axle ratio when buying a new pickup/SUV is a benefit, not a liability

By Bruce W. Smith / ©2008 Editorial Services 

Whenever I wander through car dealership checking out the new pickups and SUVs I never fail to hear other tire kickers ask about the fuel economy of a tow vehicle they are potentially interested in buying.

Fuel economy is a very important topic, and in some instances is the deal-maker or breaker between one vehicle and another.

Ironically, after the purchase, the subject of fuel economy takes a back seat to overall performance and is seldom mentioned unless it’s to brag that your truck is better than the one whomever you are talking to drives.

One of the most important questions a new truck buyer should be asking is, “What axle ratio is in this truck?”

Fuel economy is an important issue when buying a new tow vehicle. But it doesn’t have the performance impact of having your pickup or SUV equipped with the right axle ratio.

Axle ratios play a huge role in a pickup or SUV’s overall performance—and the optional ratios offered by just about every manufacturer don’t have as much of an adverse effect on fuel economy as one might expect.

All too often a buyer of a new pickup or SUV will not even think about what axle ratio is in the vehicle.

The larger the trailer or load, the higher (numerically) the optimum axle ratio. Pickups towing big 5th wheel trailers do well equipped with 4.10:1 axle ratios.

The thinking behind the decision to stick with the base axle ratio, which is typically 3.08:1 or 3.42:1, is the ratio comes standard, so that’s what the vehicle manufacturer feels is the best setup.

Or, if they do inquire about a “lower” (numerically higher) axle ratio, they are told by the salesperson the other ratios offered by the manufacturer will drastically cut down the vehicle’s fuel economy numbers.

Both trains of thought are more likely to lead to dissatisfaction with the truck’s overall performance than doing much to hurt its overall fuel economy.

The truth is, vehicle manufacturers offer optional axle ratios for one reason: to improve the vehicle’s acceleration and towing performance.

AXLE RATIO FACTS ON FIGURES

A lower (numerically higher) gear ratio, such as 3.55:1 to 4.10:1, provides more low-speed wheel torque, which means it takes less throttle to get the vehicle and the load it’s carrying or towing moving.

More low-speed torque at the wheels is a welcome help when the fishing boat is heavy, the ramp steep, or there’s a slide-in camper or load in the pickup bed in addition to a trailer of one sort or another in-tow.

(Diesels, because of their massive low-rpm torque, can get by with 3.55:1 or 3.73:1 ratios if trailers weigh less than 8,000 pounds.)

Wth a lower axle ratio you can ease into the throttle and the tow vehicle will respond a lot quicker than it would with the “highway” gears that come as part of the standard equipment.