Tire pressure - tire wear

True in the bias ply days, but I don't think so with radials.

I keep mine at 42/40 and they have worn as evenly as I can discern after 25,000 miles. In fact, they look nearly new.

 

Jerry's cheating, driving a plug-in, lol.

One thing I think: significantly raising pressures has got to increase suspension and wheel bearing wear. How much is debatable, but tires have flex, are able to absorb some of the shock of pot holes, speed bumps. Increasing pressures reduces that flex.

I raise pressures above spec, but just 2~3 pounds at the most.

As an experiment: drop you pressures to spec for the next tank, see what it does to your mpg? Then next tank just raise it say 3 pounds, see what that does.

 

First of all, everything (MPG/wear/rolling resistance vs. pressure) is going to be specific-tire dependent. We can generalize that higher pressure will increase MPG There is some lack of data and disagreement as to how much MPG improvement to expect. My current thinking is highway driving maybe less MPG bonus due to wind resistance taking over.

 

The hypermiling community is quite adamant that it increases tread life on today's steel belted radial tires. The opposition has been quite unable to show evidence to the contrary, essentially all their claims derive from the tendency of old fashioned bias ply tires to 'balloon' and prematurely wear out the center of the tread. But steel belted radials don't 'balloon' there, the steel belts prevent that expansion.

So tire pressure is a tradeoff between several competing and conflicting goals. The primary downsides of increased pressure are rougher, harsher ride, and the possibly increased suspension and bearing wear (plus interior rattles) that Mendel mentions. The later has not been quantified, so its degree remains an open question.

 

People are very passionate in their ideas about tire pressure.

My feeling is, that Toyota wants the best MPG possible for their vehicle. As well as the best safety, and synergy with the suspension and braking system. And they have the engineers that build the vehicle.

Therefore? I just inflated to the recommended PSI in the door jam and called it a day.

 

LOL!! It's pretty amazing till you notice that it's a PiP. My average will be dropping a bit soon since I'm on a several thousand mile vacation trip with not much plug-in availability. I might not get Fuelly updated till we get home in about a week and a half.

While many people are really passionate about tire pressures, the only thing I feel strongly about is that they not be under-inflated. My experience so far is that my tires wear evenly at my pressures. Whether they wear faster or slower is impossible to know without years of testing. My theory is that, since they flex less, they stay cooler and don't wear as quickly. But I do not know. Increased bearing and suspension wear is a plausible theory and I greatly respect @Mendel Leisk's always well-considered posts here, but I'm not aware of any studies on that. He may very well be right.

So, as @fuzzy1 said, it's a tradeoff. Nuthin' wrong at all by doing what @The Electric Me does and keep them at the factory spec. It won't make a huge difference, so I suggest doing what's comfortable for you.

 

This is a timely topic, as just this morning I let air out of my tires.

I've tried a variety of various tire pressure settings in the last year. For me, it just comes down to personal comfort. There was never any discernible increase or decrease in gas mileage, so I set the pressure where the car feels and rides the best.

Maybe the GEN 4 has firmer suspension? Any psi at 40 or above, made the car feel so rough and bumpy. Or maybe it's just my Michelin tires. However, I am now just 1 pound above factory recommended specs. I am also hoping this decrease in air pressure may help with the tire noise problem I am having.

 

I am pretty sure the shape of the curve starts bending over at higher pressures, so there is a bigger penalty for being under pressure, but less bonus for being over pressure.

 

not in radial tires. it's well documented that tires wear less with more pressure. as for that suspension wear Mendel talks, I would like to see results rather than speculation.

 

....sorry I am talking MPG relationship with tire pressure...I don't know about wear...I don't think much about wear, but I am worried about having more rubber on the road for traction in rain and snow

 

how about evidence?
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=14&ved=2ahUKEwihy-Tz8oXdAhUNTKwKHbINB7IQFjANegQIBBAC&url=http%3A%2F%2Fwww.chicagoagr.org%2Fourpages%2Fauto%2F2008%2F11%2F14%2F46992311%2Fdominic%2520Corbett.ppt&usg=AOvVaw0ZmDGEoASEqMlUnhBeO7wO
Looks like a science fair project, should be easy to replicate. The difference was small, but longer stopping with lower pressure. This was for dry and no ABS. There could be different results in different circumstances.

you should worry about wear too, the longer you ride on worn tires, the worse stopping distance. Ideally for stopping distance, buy new tires, over-inflate same for less wear and change when worn out to 50% or so.

 

2 GEN III Prii and a few sets of tires later I have found the sweet spot for wear, safety, comfort and mpg is between 42F/40R and 40F/38R.

 

My interpretation of his data is that his sample variation greatly exceeds any effect he is trying to study. Put some basic statistics on them, and you cannot discard the null hypothesis.

A more controlled study with a much larger sample set is needed.

 

The "tire checker" at the dealer just told me the Michelin Premier is a good tire, but it's noisy.

Yeah, dude... I know!!!

Louder because of the shallower tread, and the special rain groove tread that expands over time.
(I was looking at the Defender, at Walmart. Good price.)

 

Is this standard on most tires now, even cheap ones? Or do I have to look for it in the specs?

 

Steel belted radial tires are standard now, and called out as a requirement for Prius and most other cars. But the construction, steel belted radial vs bias ply, should be called out in the specs.

 

It sure is nice to go back down to normal factory PSI levels. It's like a different car. No more harsh or jarring ride (only if you hit a big bump or hole). The suspension is quiet again... no more moans or groans or clinks or clanks. And the gas mileage is just fine... hasn't changed in 400 miles. And my dentures no longer fall out!! Even the tire noise has decreased a little. It's all good.

 

For me speculation is enough. Tires are consumables. And I know the suspension is sustaining more shocks with pressures increases: I can feel it. Plus our tires tend to "age out" before they wear out.