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Grit_dog
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Sep 24, 2021

Tire pressures matter....lol

Because folks often post looking for assistance correcting ill-handling manners of trailers, figgered I'd share.

Last night I grabbed a little 18' cargo trailer from work to bring back to another project across the state.

Truck is a new 1/2 ton Chebbie with 50psi max tires. I had low 30s psi in the rear tires as the truck is mostly a commuter rig with nothing in the bed.

Had a bit of wind, but once I got er opened up on the interstate, the trailer was kinda squirrely. Shouldn't have been, because it had a bunch of tongue weight. Truck was squatting pretty good.
Remembered I had commuter air not towing air in the back tires. Aired up to 50psi (hot) at a gas station, which was 43 psi this morning (cold). Trailer pulled good then. Totally different.
  • Tire pressures are indeed critical in vehicle handling, especially “directional stability.”

    Learned how much so years ago racing sports cars. Proven bringing some firewood home in a bud’s truck. We got on the 2 lane country road after loading up and he had to use the entire roadway, it was so squirrelly. That was at only 35 mph. Stopped at the gas station at the main road and found 20 psi all around. Took the tires up to max sidewall pressure and truck was fine even on the interstate.

    My X5 BMW calls for 33 front and 41 rear and at those pressures tows like a dream. A bud who tried it with 35 all around in his X5 was convinced the X5 was a horrible tow vehicle until he tried it at 33/41, when it ran like a train.

    Seriously, first thing to check before springing for anti sway is tire pressure.
  • My camper trailer is pretty light, about 9300 GCVW. I have aired the rear tires up to sidewall max to tow it a few times. The handling with that trailer does not improve much, if any. And most trips we set up camp and use the pickup to run around. With no trailer, and hard tires I notice stopping and quick lane changes, she does not track as well. This tells me, if I had to make a sudden stop, or swerve with the trailer, I will be better off with door post pressure.
    Now I do run the steers about 10% below post when in town, but at post if going to drive more than 20 minutes at a time at speed.
  • Exactly Grit!! I schooled your tire jocky buddy (C Rer), on this very issue. I know tire max load may be reached at near door sticker pressure, but with heavy tongue wt, more air is better, usually tire max pressure, as marked on the sidewall of a 1/2 ton truck.

    I challenged him, to borrow a trailer, since he didn't own one, take it for a tow, with 1K+ hitch wt. Now air his tires to max pressure (51 psi, IIRC) take it for a tow, and report back. He did finally admit, that some more air might be better, but I don't think anyone trusted him to tow their trailer.

    I am referring to max sidewall pressure on truck rear, and a bit more than door sticker air on the front of a 1/2 ton, when towing a 7K+ GW trailer.

    Jerry