Tow Vehicle Bounce

I saw a film in the Air Force where they put a pickup on a dynamometer with low tires (only 10 pounds low IIRC) and you could watch as the heat built up in the tire until it reached the vulcanizing temperature of rubber. with smoke billowing the tread came off and then the tire blew out. I think the film was put out by one of the tire companies but I don't remember which one. (I think it was Firestone) I was teaching driver's training (for military vehicles) and showed the film to the students to illustrate how important it is to have the correct tire pressure. I talked to a factory rep from Michelin and he said that Michelin recommends inflating the tire to the pressure on the side of the casing. I almost always run Michelins and have followed that advice and gotten amazing tire life - (70,000 -80,000 miles)

The problem with inflating tires to the maximum pressure marked on the tire is that it makes for a very bumpy ride in a pickup truck.

The spec on the door says 55 front and 80 rear. Tries are rated for 80. When running empty, 80 pounds in the back and it feels like the rear end is bouncing in the air. So I keep 55 front and rear when running with no cargo and air up the rear to 75 when towing. 80 psi is a real hard LT tire.

I went from 35 PSI (yes, I check at every gas stop - and I know that it should show a little high after the first stop of the day, as that's cold pressure vs. hot pressure) which is what Chevy recommended up to 44 PSI (max sidewall pressure) in the rears, I left the front alone (35 PSI) as the bounce really does seem to be coming from in back.

Let's just say that I would never have believed it would have done as much good as it's done. I would never have guessed that much (most?) of the bounce was just underinflation! But I've still got some bounce - we'll see how things travel on my next trip, and that will decide what if any additional work needs to be done.

I'll measure my bumper drop next time I hitch up, although I suspect it's not much more than an inch at most.

(I'm having a good day - backed into my extremely tight driveway which requires a hard turn while backing on the first try with no spotter, centered the wheels on the driveway like I like, and - best of all - the neighbors were watching! After having gotten rid of most of the bounce, this has the makings of a great day!)