Stupid tire store conversation about air pressure

I don't understand why you would want to sacrifice comfort and stability by increasing the tire pressure beyond the recommended amount for the car itself. And as for the tires being rated for 35 psi I'm sure he really meant the car not the tires. When you over inflate the tires ground clearance increases too so it's questionable whether you gain mpg. Air resistance might offset the less rolling resistance. Ultimately all you may have gained is a rough hard ride and premature weakening of the front end. mark_

Because it doesn't sacrifice comfort or stability. Experience shows this.

It may be questionable--everything is questionable--but it does gain mpg. Experience shows this.

If I didn't feel the ride was comfortable, and especially if the car was less stable, I wouldn't keep the tires at 42/40, but my ride is perfectly comfortable and stable that way.

Oh no, he absolutely meant the tires when he talked about their sidewalls not be able to handle anything above 35 psi.

This isn't something I've just made up, and it's not just common knowledge in the Prius newsgroups, mailing lists and forums, it's something I've read about for years. Increasing tire pressure up to near the maximum rating increases fuel efficiency.

I don't have a rough hard ride.

Never had any problems in my previous cars.

What have you been smoking???? Cars themselves do not have a maximum tire pressure, they only have a maximum recommended wheel/tire dimension. The pressure limit is set by the tire manufacturer to keep it within the required dimensions and physical stress limits of the material used. For your interest the Prius is shipped everywhere else in the world outside of the U.S. with Michellin Energy tires which have a maximum pressure of 51 psi which many drivers use (and the ride is NOT noticeably rough at that pressure).

With that statement you obviously DON'T have any experience in inflating the tires to higher levels on the Prius. If you did you would KNOW that it DOES improve mileage performance.

I'll just note that the inflation over the Toyota recommended pressures

35psi front, 33psi rear, started back with the Classic Prius. Many owners noted premature tire wear, particularly on the edges (which is usually an indication of running the tires at too low a pressure). (But a few stuck to the Toyota recommendations and didn't notice any problems.) Many owners then tried increasing their tire pressures up to the max. cold pressure on the OEM tires (Bridgestone Potenza RE92 XL) of 50psi, and then backed down to where the ride felt comfortable for them, which was usually in the 40psi range (add 2psi in front). A nice side benefit of longer tire life was slightly better fuel economy. (These OEMs would typically wear out by 30,000 miles.)

When the NHW20 Prius came out, people just followed the recommendations that were there for the Classic. US OEM tires (Goodyear Integrity) have a max. cold pressure of 44psi. Again, a few have reported uneven edge wear...

I have yet to see a report from a Prius owner reporting uneven center tread wear, indicating that the tires are overinflated.

Mine have been at 42/40 for the past 10K. Tires were rotated at each 5K service interval. According to my 15K service report tread wear is uniform across the surface.

I *think* he was making a joke.

I didn't get that feeling at all and still don't. What gives you that impression?

Because his statements were kinda out there. Let's let him tell us if he was or was not. In the meantime don't chew my ass jerk. I'm just making an observation.

Chew your ass? I was just asking a question.

What do you expect? He's a grouch.

That's true, he says so in black and white. Maybe he'd be happier with a cookie from his buddy?

I should add that you clearly have never seen me chew someone's ass in a Usenet post, because when I really do, it's rather obvious to everyone.

Ok Mark, get in here....you got some splainin' to do. How can a car be rated to have tires that are inflated to some certain pressure? And if they are, do you really think the car itself will be raised some amout that will raise air resistance enough to offset mileage? I didn't even conceive that you may be serious, so said you "may" be making some kind of joke. You had to be joking, right? Maybe Mike's right, maybe you were serious? Sorry Mike, I really thought his post was for humor and that that was obvious because it was so far fetched, so I got defensive when I made what I thought was an ovious observation, that he was kidding. Looking back, he gives no indication however that he was though. I'm gonna go back and hide in my garbage can for a while.

I'm going to get my pressure gauge and my feeler gauge and check this out. I'm thinking the car will be raised less than .001 inches.

I found a low rolling resistance tires in the Toyota parts department for $45 and decided to let the shop mount the tires. I have 40 psi pressure sensor caps and also asked to have them inflated to 42/40.

When I picked up the car, all of the pressure caps were green and though they'd ignored the balancing paint marks, there was no obvious balance problem. Then Sunday, I checked the tires and discovered they'd inflated the tires to just 37 psi, the minimum that shows green on the pressure sensor caps!

Yes, I'm going to buy 50 psi pressure caps now.

Since my tires are rated at a maximum 51 psi, I'm running 50/48 and they are fantastic. They are quieter than the "Mastercrafts" with worn edges (I'd bought a used car that had 32 psi in the tires.) It handles great and the ride is perfect . . . precise and efficient.

Bob Wilson

Don't worry about it, I could tell something else was up.

What got me about about his post was that I've seen him posting here many times before, so I thought that surely he'd seen the tire pressure discussion numerous times before, yet he sounded like it was brand new to him, but the thing that _really_ got me was when he told me he was sure about what the guy at the tire store really meant.

I got a kick out of your musings.

Thanks!