Tires: Anybody have Michelin Premiers?

Just one observation star man. You need to allow your tyres a reasonable distance to bed in from new. As Alan said, it won't happen overnight but takes a thousand miles or so. If you swap them around too soon, it will take longer still to bed in as it corrects from the earlier tread erosion.

 

Probably like a lot of people on here I was raised in an era when we were taught to mistrust the factory recommendation, which was viewed as practically a marketing strategy to sell cars by making sure they had the softest ride, regardless of the effect on mpg and tire wear. For that reason common wisdom was to always inflate a few pounds over what the sticker said. Even tire shops were telling people that. And this was long before hybrids ever existed.

However I am now realizing that this was decades go and and even if that advice may have been true then, tire technology as well as car technology has advanced dramatically since then.

Completely unrelated but I happened to be in a nearly identical discussion yesterday about of all things mailbox placement. In my neighborhood we have some halfway decent mailboxes with metal posts and fancy house numbers, and it's costly when they get hit by a car or truck and the whole thing has to be replaced, which unfortunately happens several times a year in our neighborbood. Our mailboxes are set even with the curb and they tend to get hit by rearview mirrors when someone gets too close to the curb. I thought what if we set them back a few inches from the curb, but I didn't know if that was allowed by the post office. So I went onto the USPS website and to my shock found that the official recommendation is to set mailboxes back 6-8 inches from the curb. They even have a diagram showing this.

Mailbox Guidelines | USPS

Yet no one seems to follow this recommendation, not just in my neighborhood but anywhere, at least in the surrounding neighborhoods that I have looked at. I even asked our mailperson and she confirmed that everywhere on her route the boxes are set even with the curb, none of them are set back. I asked her would it be a problem for the mailperson if we set them back, she said no, she said look at my tires, I Iooked down and her tires were about two feet from the curb. She said I can easily get closer. Yesterday I discussed with our HOA president about possibly setting them back a few inches when they are replaced, but we think it's too late now as some utility lines were subsequently installed a few inches behind the current post location.

Again it's totally unrelated but it struck me the similarity of the situations, in both cases common wisdom is to ignore the official recommendation. But you do so at your own risk. And in the case of our cars we are talking about much more serious consequences than having to replace a mailbox.

 

Most of my noise is because of our roads and if they were to be fixed maybe I would be concerned about tire noise.
Seems like I always pick places with crappy roads to live. The Prius not being very padded doesn't help.

 

When my old Prius sounded like a 4 X 4 it turned out to be a wheel bearing making the noise.

 

Very well thought out opinion. In my practice a few extra pounds provides better tire wear and better mileage, which are two important considerations for me. I know that the contact patch may be smaller, but the way I drive I do not believe that that is worth much thought.

 

I worked at tire stores for a few years in my youth. I almost never saw the center of the tire wear that over-pressured tires should demonstrate. Shoulder wear from under-inflation was rampant along with wear on one shoulder from toe-in issues.

 

Old motorcyclist here and cringe at thought of automobile tires on a motorcycle—-> car tires typically have belts and a noticeable shoulder where the flat tread meets the sidewall, whereas motorcycle tires are built for keeping traction at severe lean angles and transitioning smoothly from the upright driving position to the knee-scraping position. I simply would not want to drive a bike with car tires and then lean suddenly into a curve—unpredictable results! (Have also crashed and do not wish to repeat.)

But car driving has a different suspension geometry that keeps the tire in the upright position. I have seen videos of under-inflated tires as speed increases and the contact patch decreases as the patch front edge kind of “lifts up” at high speeds. Cornering puts different stresses on the contact patch, but again an under inflated tire can have bead separation from the rim at lower speeds. I’m sure you have good points for severe over inflation, but not sure what holds true for moderate over inflation in the range of 5 psi. I heard state police officers in the 1980s state that they routinely ran their patrol car tires at 5psi over recommended pressure for better handling, but I do not know if that is still done or not.

 

I think the tendency back then was for tyres to lose pressure regularly - you almost always had to add a bit, even weekly - meaning that a lot of tyres which were neglected were running at under-inflated pressures. [EDIT - no wonder they wore on the shoulders]

Radial Ply tyres now have less tendency than cross-plies to distort and lift off the road from one side - still they'll sit flat on the road at quite a few PSI over.

 

The idea of state troopers knowing better than tire engineers is laughable.