tire pressure

Tires tend to lose pressure over time.

Correcting for temp fluctuations is one of the reasons for checking your tire pressures frequently.

 

tires also tend to lose pressure when punctured by a road hazard, such as a nail.

Oh, and 44psi is not close to the "max" pressure. Imagine what would happen if we hit a bump. The bursting pressures is probably over 90psi.

 

It's actually somewhere north of 200 psi. I have a friend who has a connection to someone in the tire industry who has done max pressure tests and it's way over 200 psi. For obvious legal reasons he doesn't want the the brand or the exact pressure revealed in case some idiot would go out and try running a couple hundred psi in a tire and get hurt or killed.

 

I've been using 44/42 for many years now.

It's no big deal. In fact, it's down right impressive that tires nowadays wear so evenly with higher pressure.

Routine topping off is needed. They do soften over time.

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Measure cold pressure (before driving). If temps warm alot in a short time and you don't want a couple extra psi, you would need to bleed a little. Don't bleed air after driving, because that expansion is built into the max number or other recommended pressure you wish to follow.

 

The only time mine have been under 60 psi was when I left the dealer and went across the street and pumped them up just over 15K miles ago.

 

I've been running 42/40 PSI for the last 3000 miles. Before that, I ran 40/38. Now I have 8000 miles and the fronts have noticeable wear in the center of the tires --- just like you might expect from over-inflating. So... I just rotated the tires and went to 37/35 PSI.

I'll closely monitor MPGs, but if there is no significant loss in FE, I'll stay with the lower PSI setting.

 

That's the maximum cold psi measurement (when the tire's psi is stable because it has not been run on for a while, e.g., 3 hours), whether in cold or hot weather.

Changes in the ambient temperature which cause a change in the tire's psi is one of the reasons why we're supposed to check our tires' psi regularly.

 

Yep, got mine at 70psi, but I'm about as nutty as Larry .

Set it to 40 something. If you ever get nutty, pump it up to 70psi. The fun part is watching the mechanic check the pressure at arms length since he thinks the valve stem is gonna explode.

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I use 50psi front and 48 psi in the back.

 

Dan., how did you decide on 70 PSI? Testing to see what tire pressure gets you the best mileage, or research on your particular tires?

 

For the Spinal Tap fans out there... My gauge only went to 70 . I guess I'd go higher if I could accurately measure it, but I didn't want to create a pull by having the left at 80 and the right at 78 and simply not having the gear to see the difference.

As you get higher, the ride does get kinda bumpy. Above 75 I think my fillings would probably rattle out of my teeth.

The guys at the Toyota Dealership always get a kick though. Last time I brought it in they were poking around at my grill insulation.

:der:

11011011

 

Word of warning, I see your in Canada. Didn't realize that on my last post or I would have warned you. High pressure is a very bad idea if you ever have any chance of coming anywhere remotely close to snowy or icy roads.

I'm in Texas. It was 80 F (27 C) this afternoon. No snow here.

For Canada, stick to the door panel pressure or the pressure recommended on your winter tires!!!

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Practically nothing.
The increase in temperature approximately counterbalances the usual slow loss of air. The one or two additional PSI you may see if the weather suddenly gets warmer doesn't make a significant difference. Just leave it in. I never ever let any air at all out of my tires. I just have to top them up less often when the weather is getting warmer.

Please also remember not to adjust your tire pressure if the car has been in the sun anytime during the last couple hours. If the sun has shone one side of the car, the tires on that side will be warmer, and will give a false reading when you measure the pressure. It is best to measure tire pressure after the car has been sitting in complete shade for several hours.

 

The tyres kept bursting at 72?

Very high pressures may cause harm to parts of the car that arent going to cope with vibrations well. You know, the expensive electronic kind.

 

I was nervous when I pumped mine up to 50-48...... now I'm comfortable with it, and mileage is better.... Warning, I no longer have the OEM tires. I'm running Michelin Hydroedge's in a 205 size.

 

Lets see now, the Toyota engineers were smart enough to design a very complicated and efficient car. Remember, the main goal for them was to design a fuel efficient car, and that includes the tire pressures. But from what I read on this forum, they were totally stupid when, after running hundreds of hours of tests of tires at various pressures, they decided to "arbitrarily" recommend 35 and 33 psi for the Prius. Come on now, folks, there is a lot of wrongheaded thinking going around. Sure, you want the best gas mileage, but there are other things to consider that the Toyota engineers probably figured in. For example, the extra wear and detuning effects on the suspension components and the rest of the car. As a fellow engineer, I resent the second-quessing by many untrained people in this matter. If the tire pressures are so totally wrong, the rest of the car must also be quite poorly designed and therefore you should not have bought it.

 

In Texas we have amazingly smooth roads. I've traveled to the East Coast and the roads were very, very rough. Riding on 70 in Houston is about like riding on 40 in other places.

Main reason we have good roads here is what I like to call the "Texas Public Works". If there is a strech of road that hasn't been rebuilt in the last 10 years, then it's time to build it again. Guess it keeps un-employment down or something. One I-10 heading out of Houston has been under construction for the last 60 years. Go figure.

As for driving on high PSI. The only person I recommend it to is Me. But for those curious about a statistical sampling of drivers, you can watch to see how long I can go without spontaneously combusting .

As for the burst point, I think it's somewhere north of 200 PSI for the tires on the US Prius. Bursting a steal belted radial is far from easy. There are some driving safety organizations that recommend higher PSI for non-winter roads (50 PSI range). I won't weight down the thread with it, but if you want to see it PM me and I'll pass it along.

So... Don't go over 42 PSI.... Unless your Dan .

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Not that I'm smart on this subject (especially not smarter than "Toyota engineers") but isn't possible that a softer (more comfortable) ride was the main factor in determining the recommended 35/33 psi? If that's the case then is it OK for some people to choose that a higher psi with better fuel economy is an acceptable alternative?
Gabe