Door Pressure Sticker Reading on V

I know you've already found it, but for those later readers who may still be wondering, here is a picture beneath the steering column, showing the TPMS reset on the left and the PCS on the right:



I hope someone finds this helpful. I remember feeling something move to a place it should not have gone as I was trying to get this photo.

 

Yes I agree with your observations. I have tried several pressures with my V in the 2K miles I have had it and finally settled on 46 lbs in all 4 tires.

Leaving tomorrow on a 3500 mile trip through the Southwest, looking forward to having a great time.

 

Tom, have a safe trip and let us know how you faired with mileage and tire pressures set as you did.

Also, Thanks A Priori for the Great Pic fo the buttons I was looking for. Nice job!

 

I'll keep a log book of fuel used and miles so I can compare displayed to computed mileage. Also for part of the trip I can compare this new Prius to my Gen2 which should be of interest.

 

You are going to destroy a set of $500 tires to save a few bucks on gas. It doesn't sound like a very good trade off to me

 

You are most graciously welcomed. Glad it helped!!

How are the tires going to be destroyed? Inflating the tires to a pressure higher than the number recommended by Toyota is not going to damage the tires (I'm not addressing pressures above the sidewall max printed on the tire). In fact, it is going to allow the tires to last a bit longer and wear more evenly.

 

2-4psi over recommended pressure maybe, 46psi, something like 14psi more than stock? That's almost the recommended maximum tire pressure on most tires!! (51psi)

Let's not even get into the contact patch from 46psi vs 32psi.

 

Have you looked on the tire for max tire inflation? One should never exceed the MAX MTI

 

Do you have michenlins tires on your V?

 

Yes - it's something like 51 PSI. I'm only running 38/37, though there are plenty of sports car enthusiasts and hypermilers that don't mind running anywhere from 42 to 52. The low profile tires on the V make for some pretty sharp jolts if you happen to hit a pothole etc., so I doubt I'll go much higher.

 

The car manufacture builds the car and suspension. The tire manufacture builds the tire for that suspension. Exceeding the inflation printed on the tire can put you and your family in danger. If you want to try different pressures for better mileage etc, Do not exceed the Max PSI imprinted on the side wall of the tire.

If you have a S, T, V, Z etc rated tires, you must stay with it and follow what is on the door sticker. ( like 93V )
When you read the tire size off the tire, read the entire string of information.
Like P 215/45/R17 93 V.

The P indicates passenger tire. 215 is the tread width, 45 is the aspect ratio( which also is the height of the tire, R indicates radial, 17 is the rim size and 93 V is the load index ( has specific number of steel other construction materials and also rubber composition.( some are hard rubber and some are sticky or soft rubber composition.
The important thing here is not to exceed the imprinted maximum tire inflation for your specific tire.

 

For your comment on my safety remark, you can refer to other threads here and on Edmunds that have worn out that discussion.

Your comment above is even more general than mine. How do you know that? There is an optimum pressure setting for each tire and it's specific to the car. The maximum pressure is just that, one not to exceed. But suspension settings, the weight of the car, etc (as well as comfort) all go into the design Toyota set for this particular application. Tires have to be made with flexible settings because they are used on various different vehicles. But each car has a design. Individual owners can ignore the designers selection, but when yo do you have decided to ignore the particular traits of the tire that they intended for the setting on the door. It may be a rougher ride, but better FE. I can't imagine that Toyota wouldn't have opted for a higher setting if it meant a 10% better FE. Perhaps when the new CAFE numbers go in effect all makers will use higher pressured tires.

I'm not saying you shouldn't raise the pressures. It's all a trade off. However there is a point where you do trade off safety. I don't think it's necessarily 40 psig, but certainly once the car starts "skipping" over rough roads losing contact, I believe you have gone too far.

Yor comment of the tire lasting longer and wearing more evenly is certainly too broad. Again there is a certain point where that is not true.

 

That is absolutely not true. Please refrain from perpetuating this myth. For those of us who use the term hypermiler, it is a great disservice. I believe I can speak for all hypermilers, that we don't practice, condone or advocate drafting. Drafting has been mentioned by the opponents of hypermiling as an example of how unsafe hypermiling is. The thing is, hypermilers don't draft. If you are drafting or see a person drafting, that is not hypermiling.

I ran my Goodyear Integrities at 44 psi the whole life of the tire. I changed them a few weeks ago at 61,000 miles. Running at max sidewall saves the tire, not destroy it. BTW, the edges on the integrities still wore out first.

 

I agree with A Piori.

Some of the new tires have max sidewall of 51 or 52. Are you still going to go with the 32 psi recommended. The tire would be almost flat and it could be dangerous in a hard turn.

 

I went back to see where I had commented on a safety remark you posted, simply to refresh my memory. Here is your remark, followed by my comment -- really, it is much more of a question:

I've read through numerous threads on PC and elsewhere, and I haven't found one thread that substantiates a claim that filling a tire to above the (car) manufacturer's recommendations necessarily is unsafe. I do recall reading someone's empirical study suggesting that the car manufacturer's recommended tire pressure settings are not the best level for safety purposes. Instead, the tire pressure setting seemed to be good for a soft ride, but a firmer tire would handle better and, depending on the pressure, respond better in heavy braking.

No. I haven't pointed you or anyone else to that thread or any other. But, I haven't made the claim there is a safety trade-off by inflating the tires on a Prius V to 40psi. Am I throwing down the gauntlet and challenging your claim? No. I am curious to see the source of the information, because the knowledge I have accumulated doesn't fit with your statement. If there is an empirical study, I'd like to see it and read it to determine whether it will change how I handle max pressure issues on the tires on my Prius V.

Really, I have a feeling you and I are much in the same place, though I do not have qualms about exceeding 40psi on this car and with the tires I have. It seems to me that 40 is a bit more of a tipping point for you, and I'm just trying to find out why:

You've also taken issue with my response to Cossie1600's comment about damaging a set of tires by using pressures above the Toyota recommended level. Here is Cossie1600's comment, my reply and then your comments:

I don't know how my comment could be "too broad" -- it is a responding to a statement I clearly find to be over-reaching. Even your comment accedes to that when you note that "there is a certain point where it is not true." This means, of course, that there is a point where it is true. I do not believe, and I don't think you disagree, that the Toyota recommended pressure is a point of departure, below or above which point driving is unsafe and tires are destroyed. It is a matter of degree and not one of instantaneous change. Our difference of opinion appears to be only that you do not wish to exceed 40psi, yet I do.

I have particularly challenged the statement due to my own experience, as well as that of others expressed for years here on PriusChat. Once I increased the tire pressure on the OEM Integrity tires on my 2007, I found not only that handling improved, but also that the tires wore better. I discovered this by having the tread checked at a local tire store. I had heard of the OEM tires' short lifespan, so I had checked the wear early. I had the same folks check it later, and they gave me a different story on wear and expected life. I also inquired about wear patterns, and I was told the wear was even. Before, after less than one-half of a year, I was told the edges were wearing unevenly.

My story has been retold numerous times on PriusChat. What I had not heard before was a claim that going above the Toyota-recommended tire pressure would destroy a set of tires. Because my personal experience is directly contrary to that statement, and because the statement appeared to me to be illogical, I commented as I did. I've done so not to attack, but to point out much what you have -- that there comes a point where the effect of changed air pressures does more than simply increase FE or save tires or change handling and braking, and that point is not defined by one recommended pressure setting.

Much of what you say is true, but it does not change the fact that we do not know what has been "optimized" at a particular pressure setting. Is the recommended tire pressure the optimum level for braking, for steering, for fuel economy, for ride comfort, for general safety? I can understand a company wanting to preserve itself from claims a car is unsafe, but if safety was the overall reason for the tire pressure, wouldn't the car have an attached safety warning for that reason? Just as you've noted, increased tire pressure can cause a bumpier ride and increase fuel economy. It also can improve handling (to a point) and stopping ability (definitely to a point). Low pressure presents its own vagaries, too.

Don't forget that the OEM tires for the Prius V are not one model -- they don't even come from the same manufacturer. Though the three tires that are each OEM (Toyo Proxes A20, Michelin HX MXM4 and Bridgestone Turanza EL400) all are the same size, their other characteristics are different. They have different wear ratings, for example, so can they each be treated the same when it comes to setting a pressure for optimum wear?

The Toyota engineers are wonderfully brilliant people, but they cannot develop a single recommended tire pressure that optimizes the things I'm most interested in optimizing with the tires I have, the roads on which I drive, the way in which I drive, the weight I carry, etc.

I will look to alter and adjust the tire pressure in my Toyo Proxes based on my experience, the related experiences of others in similar situations and empirical data which may correlate to my equipment and use.

I apologize for the length of this posting, but I felt that responses and explanations were in order and would be of value. Of greater value to me than pointing out something as imcomplete or even incorrect, is doing so in a way that enhances the relationships and interactions fostered on this site and in this forum. For this reason, I wish to make abundantly clear I do not intend this long-winded discourse to be an attack on WVGasGuy (whose posts I've always found informative, forthright and, at times, rather entertaining) or on Cossie1600 (with whom I've not previously interacted). I am looking for assistance when and where I lack experience or knowledge, and I am asking more probing questions when I am uncertain of the basis for others' claims. If I've gone overboard again, please remember I've survived the heavy singe on more than one occasion, so light the flames and respond as appropriate.

 

The tire is no where near flat at 32 psig. It certainly is not dangerous at that level.

 

Wouldn't know where to start on all this.

The "safety issue is one that wore me out on Edmunds.com. I don't plan to get into that one again. It's much like the liberal vrs conservative issues. No one will agree, no one wins. But I think it's important to have all the comments out there so people know there are two sides of thought. I don't think you will ever find emperical data needed to prove any claim as it will vary from tire to tire and car to car and at the various pressures.


When I pointed out your comment too was rather broad in that "raising the pressures will make the tire last longer and wear more evenly" also has limits in its application and possibly you meant the starting point would be the settings suggested by Toyota?. Some could easily read this as saying 44 is better than 40 and that 51 must be better than 44.

Since all manufacturers recommend you increase pressures for high speed driving, there certainly can be an implied safety message there. Heat will destroy tires. Underinflated tires causes sidewall flex and flex causes heat.

We are fortunate to have all the safety features built in (skid, traction control) as a backup for any errors in judgement we may make.


We're not in total disagreement. We just don't necessarily agree on the details

 

Humm, you speak for all hypermilers? There are people that consider themselves hypermilers that indeed do draft. They may consider themselves as "the next level" of hypermiling (and I may consider them simply crazy). However they consider themselves the "ultimate" hypermilers.

Granted it's a very small number, but I don't consider it a myth, it's simply the radical fringe. I read of one guy that pushed his car a short way every morning to get to a downhill portion of his route to have his engine on as he was going downhill. That's not radical, it's crazy. Drafting is even more crazy. However they are hypermilers. Perhaps they give "hypermilers" a bad name, but none the less....

I don't see how you can simply throw them out of the hypermiler "group" of believers. Could be that the handfull of people doing this don't consider the masses of people calling themselves hypermiles as dedicated to the term?

 

I know. I gave you too much fodder!

I agree it isn't a simple issue, and most of us will have a starting point (or viewpoint) we don't want disturbed. If we can lay out the main issues, and do so civilly and with a willingness to continue talking with folks, then we'll do about as well as we can.

I think the fact it varies from tire-to-tire and car-to-car, as well as for the various loads and purposes the car is used, all point out the fact that we must be careful about making blanket statements that higher or lower pressure is better or worse. The question is better put: When considering fuel economy, is it better to inflate above the Toyota recommended pressure? The answer is better stated: Yes, to a degree. You must also consider weather conditions, how much weight is in the vehicle, what speeds you drive and what other precautions you might take to maintain safe driving.

OK. I tried to make it clear that I was only discussing pressures below sidewall max, but perhaps non-Prius V people are reading this and thinking that 46 is just fine (even though it is above the sidewall max of their tires and not ours).

True. The same may be said for weight carried.

Most of the time, yes. I think you'd agree, it's still the safety feature between the ears that will matter most.

Total disagreement!? Don't get me started.

All I can see is that you'd rather stay closer to the Toyota recommended pressures because of a concern for safety, while I believe the pressures I utilize (38 for the moment, but normally 43 -- on a 51psi max tire) are just as safe -- if not moreso for the kind of driving I do.

If we have to come to blows on it, can we at least do so in WV?

 

Even with the manual it took me several minutes to find it...the manual makes it look as though it's further forward (toward the driver) than it actually is.