Tires Croaked Early

At 15,896 miles, I punched a tool blade into an OEM tire... destroying it. I wasn't too thrilled, since there was at least 25,000 miles of thread left. And since I had experience with the Classic tires, I can definitely state the OEM for the HSD are tough enough to sustain typical use.

So I agree, definitely verify your alignment isn't off. That will chew through a tire fairly quick.

You'll want to purchase replacement tires with a much harder rubber. There are lots to choose from.

In the future, you'll likely want to maintain a higher tire pressure too. That is a plus for both cornering and the life of the tire itself.

 

This was also noted in the latest Road & Track, where their OEM tires expired at around 23K miles. I'm sure they also tend to drive it with a bit more... spirit... than most as well.

 

Uh, no. High tire pressures reduce the contact patch of the tire. Since some of the grip between a tire and the road is due to mechanical interlocking (at a microscopic level) between the tread and road surface, more contact area equals more grip. But lower tire pressure can cause poor handling due to sidewall flexing, and sometimes for sustained hard cornering (autocrossing), you have to overinflate just because the tires will overheat and fall apart if allowed to flex too much, even if it reduces grip slightly. Consider that road racing tire pressures are much lower than autocrossing tire pressures for the same tire. So there is some tire pressure for which grip is maximized, but it isn't the highest pressure the tire is rated for.

F1 tire pressures are around around 22psi front 18psi rear.

 

As previously posted here and also told to me by my Prius tech is EXTREMELY important to keep the tires at 42/40 air pressure to get good life out of the tires.

 

Sorry, that is absolutely false.

In the past, it actually was true. But not anymore. Construction of tires is dramatically better than it was years ago. You can confidently use pressure all the way up to the maximum specified by the tire manufacturer.

We have proven that with countless miles of data. I alone have racked up over 60,000 miles showing the contact patch is absolutely flat. Wear is even all the way across the tire surface.

Try it. You'll like it.

 

Sorry, but it's basic physics. Even the Prius can't break the laws of physics. Ignoring the stiffness of the tire carcass for the moment, (tire pressure * contact patch area) = amount of weight supported by the tire. Lower the pressure and the contact patch increases in size. Since the tire carcass isn't as flexible like say, a thin latex tire tube, this relationship isn't exact, but it's still correct that decreasing tire pressure increases contact patch.

A modern tire's tread will stay flat across its width for a wide range of tire pressures. But that just means the contact patch grows in size front to back (in the direction that it rolls) rather than across its width.

 

I believe you are misunderstanding what "maximum" means nowadays.

The laws of physics work in direct correlation to that value... which is clearly not the same as it was in the past, due to the much improved construction of recent tires. Tolerances change as materials change.

Note how tire manufacturers discontinue tires rather quickly. This is in part due to performance increases. So "old school" knowledge eventually has to be re-evaluated.

 

Consider...

If you run your tires at 35 psi, you've got more surface area than at 40/42 psi... no matter how you spin it. No matter what fantastic advances have been made in rubber over the last x years, if you run your tires higher at a pressure higher than the recommend, you're still putting the same amount of weight (your car) onto less surface area(your overinflated tires). You're going to wear down that portion of tread quicker, no matter what.

 

Jonnycat, your assumptions are flawed I'm afraid.

If you under-inflate or over inflate so much that there is excess pressure on the outside edges or center of the tire, then yes, that portion will wear faster, but within the normal inflation range of the tire up to and including the max on the sidewall, that doesn't happen with modern tires.

Higher inflation does of course have plusses and minuses.

Plusses:

Longer Tread Life
Lower Fuel Consumption
Shorter Wet Stopping Distance
Shorter Dry Stopping Distance
Better Cornering
More resistance to hydroplaning
Better performance in slush and snow

Minuses:

Harsher Ride
Possible hop on very specific washboard surfaces at very specific speeds.

I must agree that if you consider that the max 'recommended' pressure is what the tire manufacturer wrote on the sidewall, then yes, inflating past that point can bring problems and is not advisable.

However, if you are saying that the max 'recommended' pressure is what the car manufacturer put on the door sill, then no, there is no tire life or tread wear downside to going past that point, just a comfort issue.

Remember, Ford put a recommended Tire Pressure on the door sills of Exploders, and the tires exploded because it was far below the Tire Manufacturers recommendation for the tires.

 

It just isn't that simple, and I'm afraid that like john1701a, you are way out of your depth in trying to discuss this topic and back up your assertions with statements supported by scientific fact. There are people reading this forum who have as many years of engineering education at world-class universities as you probably have of total education.

Let's just take one of your assertions:

Shorter Dry Stopping Distance

Lower tire pressures cause the contact patch to grow longitudinally, giving the tire more grip and shorter stopping distances. High tire pressures cause the contact patch to shrink longitudinally (the direction the tire rolls), giving it less grip. The effect on longitudinal grip is actually much greater than the effect on lateral grip since the contact patch isn't growing any wider, just longer. Why do you think that on the exact same tire, road racers use up to 12psi less pressure than autocrossers? The answer is that autocrossers need the extra pressure to reduce tire flexing and keep the tires from overheating and throwing off chunks of tread, due to the continuous high loading. Stiffer sidewalls also contribute to more precise turn-in and better steering feedback, also important to autocrossers. Road racers on the other hand, have straights where the tires can cool, and can therefore run with less tire pressure, and get a little more longitudinal and lateral grip with a slightly increased contact patch.

Note that it's only due to the mechanical interlocking that grip is increased with a larger tire contact patch. The coefficient of friction between two objects should be independent of the contact area (and therefore independent of pressure), as all that should matter is the total normal force (weight), not the area it is spread over. In the real world there are additional effects not accounted for in the simple model of surface friction.

As far as better performance on slush and snow, the jury is still out on that one. Proponents of high pressure say that with the reduced contact patch (and therefore higher pressure on the contact area), the tire is more likely to push down through the snow to a solid surface where there is some grip. Proponents of lower pressure claim that with an increased contact patch, there is more grip due to mechanical interlocking, and grip is increased. I'm in the lower tire pressure camp on this on, just based on my experience driving my Jeep off road on muddy trails. The tires conform to irregularities in the road surface better with less tire pressure.

 

<div class='quotetop'>QUOTE(priusenvy\";p=\"59588)</div>

Heh

Know what, I'd be happy to take that bet. See, the problem is that on the Internet you really have no idea who you're insulting.

I have many years of world class engineering education, and experience, but that's really irrelevant once you stoop to that kind of discourse.

I also have plenty of background data, including testing and industry reports to back up what I say, but it gets tiresome dredging them all up over and over.

There's really only one way to deal with people like you on the internet - *Plonk*

Consider it done.

For the rest of the folks here, yes, there is a difference between driving on pavement and on mud, but we're talking about pavement. Even in snow in our cases there's still an incompressible substance underneath, which is what matters for grip.

 

That good Mary!

 

I had a similar experience also a little after 11K. Dealer replaced all 4 tires with Michelins and did the alignment for free.

 

<div class='quotetop'>QUOTE(mary2al\";p=\"60590)</div>

Al,
what the heck kind of tires did you get for $125 each?? Youch.