dealer tire pressure = 32psi

Due to the heavier front end weight Toyota advises to have the front tires 2 psi higher than the rear. Look it the sidewall on the tire for max tire pressure. There are a lot of PC members who go higher than the max psi recommended in order to improve their MPG.

I've read a number of discussions on PC arguing the opposite about tread life with higher psi. I'm a believer that the higher psi has no adverse effect on tire life and that it actually results in more even wear and longer tire life.

After each service I just drive to the nearest gas station to adjust / increase my tire pressure. It makes no sense and reason what they leave me with - all over the place. I can only conclude that as owners we care about little things more than they do and can't be bothered to argue with them for such a small item.

 

I think they are correct; lower pressure gives longer life (within limits), higher pressure gives best mileage (and worse ride). So there are endless debates about ride vs mileage. Seems like a few psi would really not make that much difference either way, but others will post with more knowledge.

But the warning light only comes on when you are off by 10 psi from this setting. So you could increase your pressure back to what you want.

I use to go to an oil change place where they would fill your tires up to the maximum on the side wall. I would drive out and it felt like I had stone tires. I circled around and had them lower the pressure to the door jam values.

 

Your service dept is full of BS. Softer tires wear faster. My Integrities at 45psi still had edge wear, a sympton of underinflation.

You couldn't find any info?? How hard did you look? There must be dozens of long, heated threads about tp on this site.

 

Today, during the 10,000 mile oil change and ECU update, I had nitrogen installed in the tires. The dealer put 35 psi. I do not know what to attribute it to, but the ride seems more refined, the car seems to glide a bit easier, and early indications are my mileage is improved. Time will tell.

 

'Better' from the perspective of the tire seller, not buyer.

I'm puzzled how you could detect mpg improvement in a single ordinary day. The regular daily variations should swamp the tire pressure effects.

 

This is the same effect that made your skinned knee feel better when your mommy kissed it all better. 100% nitrogen or 78% nitrogen (pretty much what you breath) are equally "refined." Whatever pressure you decide to keep your front tires at, it would be wise to follow Toyota's recommendation to set the rear tires two psi lower.

 

Think about the physical problem of emptying a tire to make sure that it is filled with nitrogen. How did they remove all the air prior to filling the tire with nitrogen? Did they have a large vacuum chamber for that? Even if I believed the hype about nitrogen, until they show me how they removed all that bad air I wouldn't pay a dime for this "service". Besides ordinary "free" air is about 80% nitrogen anyway.

 

Your correct about the door jamb sticker; they are dead wrong about the tire life at 32 psi. I ran the OEM tires at 40/38 and they still showed a wear pattern that suggested they were underinflated (outer edges wore more quickly than the center). I'm now running 42/40 with Michelin replacement tires.

If you run 32 psi, you will wear the tires out sooner and get worse fuel economy.

 

I agree. If you re-read my post I suggested several reasons for the increase. The ECU update? the nitrogen? or possibly just inflating the tires to the correct pressure following Winter.

In my daily life, I do not experience much in the way of "daily variations." Being retired, my habits, routes and here in Northern Utah, the traffic does not vary significantly. Am I prepared to testify in a court of law it increased .... no, but my early impression is for whatever reason, my mileage efficiency improved based on the HSI readout. We shall see.

As for the nitrogen .... the cost was less than tire rotations, which are included. If the nitrogen molicules are larger as advertised, and a nitrogen filled tire is less prone to seep air ... then it was well worth the effort.

 

Whoever advised lower pressures probably grew up with bias ply tires under the Eisenhower Administration. Today all car tires use radial plies. Much worse than any effect on tread wear, lower pressures cause the sidewalls to flex more. This wears them out invisibly and may cause them to burst before the tread wears out. You don't want that.

Indeed the MPG improvement from higher pressures (say, 44/42 front/rear) is distinct and noticeable.

A "pure" nitrogen fill is harmless, but it's pointless. Don't pay more for it or drive extra to get it.

 

My new cooper tires were inflated to 38 in the driver rear and 32 all the others. So much for what they say. I wont be back there even for warranty service.

I went to my oil chg place (mobil 1) and they put free N2 in to my pressures as long as they didnt do over the sidewall max. I chose 40/38 or 2 lbs under the max for now.

I most likely will go up but for now with 300 miles only I am still breaking in the tires and the now mpg is at around 48.3 Thats not a long way off from my average 50 to 54.

 

44 front/42 rear for our Prius stock tires. The ride is a bit harsher, but the MPG is better

 

How do you decide what tire pressure to use? Some say 44/42, some say 40/38, and so on. Is there much of a difference (fuel econ, wear, ride) between these pressures, or is it just a matter of personal preference? How does someone decide 42/40 is better than 40/38?

 

I believe the TPMS warning light is supposed to come on when one or more of the tires loses 25% psi from the TPMS setting.

Thus, if the TPMS setting is 32 psi, the warning light should come on if a tire's pressure reaches 24 psi.

 

From my own experience I found my choice of tire pressures to be mostly subjective. After three pri and thousands of miles my wife and I have decided on 40/38. We arrived at this driving in our local area and taking into consideration the road considerations over several years. It's difficult to describe to another driver but we found 42/40 a rougher ride but good mpg and 40/38 a somewhat more comfortable ride and not a great loss of MPG.
As an aside noted your location as Elgin IL. It was near there in 2008 in Hanover that we were T-boned by an unlicenced, undocumented driver which totalled our 2008 Prius enroute to Nova Scotia. The bright side of things was the excellent and professional assistance by the Hanover police department and had some valuable time with our grandaughter in South Elgin meeting some really great folks.
Happy driving
Gary

 

different tires have different max sidewall max pressures listed. You may want to not go over that max sidewall pressure. Others are not so concerned about that. I chose 40/38 as the rear should have 2lbs less for safety and stability.

I used to go 42/40 in the stock tires. 2 tires had holes in the sidewalls from road hazards at 30K and the other 2 were starting to separate the belts for some reason. I was lucky to trade them when I did.

 

Note that the max sidewall pressure is the max *cold* pressure. If you've been driving for an hour the pressure might easily be higher than that; this is normal. Measure tire pressures only when they have been driven less than one mile in the previous hour.