Reader Question: Imbalanced Tire Pressure?

Here’s the latest reader question, along with my reply!

Jeremy asks: My 2002 Dakota calls for 35 psi up front and 41 psi in the rear. Intuitively this seems backwards. Why the difference, and why more pressure in the rear?

My reply: I rooted around a bit and found some possible explanations; see here. But I’m betting the higher rear pressure is recommended because of loading, the Dakota being a pick-up. With a pallet of bricks in the bed, you’d likely want the higher pressure to handle the extra weight. Dodge probably assumed most people would be loading the bed regularly and rather than advise owners to put a bit more air in the rear tires when they do so, just specified the higher pressure to avoid potential handling/braking/instability issues in a loaded truck with under-inflated (for the load) tires.

Manufacturers – the car companies – sometimes send new vehicles out with tire pressure recommendations that are lower than those recommended by the tire manufacturer, in order to smooth out the ride. It’s ok to play with inflation pressures a bit, to fine-tune ride vs. handling and so on. And replacement tires of a different type may need a bit less (or more) pressure to perform optimally, last longest – and so on.

But as a general rule, it’s sound policy to stick close to whatever the manufacturer recommended pressure is.

Some may remember the Corvair fiasco – which was really a fiasco caused to a great extent by owners not hewing to the factory recommended front/rear pressures. By ignoring these recommendations, they altered the handling characteristics of the early Corvairs in not-good ways. Of course, this is an extreme example – the Corvair was rear-engined and had a swing-axle rear suspension prone to snap oversteer – but the general point is sound.

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Got a question about cars, Libertarian politics – or anything else? Click on the “ask Eric” link and send ’em in!