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Discussion in 'Prius c Main Forum' started by TDog, Nov 7, 2012.
How do I check the tires pressure in my C?
What should it be?
You need a tire gauge to check pressure. Dealers inflated them at about 30 but people here posting more than 40 with some at 50. Mine is 45 front and 43 rear at cool temp tires after sitting in the garage for few hours.
Tire gauge...is it an app?
Sorry, been behind a wheel for only 3 months, don't know crap
This is the tire gauge I'm using.
What is psi and a tire gauge? Where will i find one?
Sorry, layman terms please
psi=pounds per square inch (a measure of pressure)
You can buy tire gauges at Walmart, Target, auto parts stores and many other places.
I bought a digital one from Target or Fred Meyer years ago that looks identical to Accutire Digital Tire Gauge - MEAMS-4021.
Do NOT check your tires when they're hot (after they've been driven, as driving on them causes them to heat up and raises pressure). You MUST check cold inflation pressure. If you have no pump at home, check the cold pressure first (to see how much you need to add), drive to a pump and check again to see how much it's risen and add the appropriate amount so that you won't be underinflated when the tires are cold.
Tire Tech Information - Air Pressure: When and How to Set also may help.
Do you not have parents w/cars? Even I knew about tire pressures way before I could drive. My parents are NOT car enthusiasts either.
The recommended tire pressure is printed on a sticker in the driver side door jam. Open the driver door face the rear of the car and look down. The print is small so bend down to read it.
the recommended pressure depends on which trim level you have (I think) To measure the pressure you buy a Tire Pressure Gage. They are not expensive and arwe about the size of a ball point pen. Under $10. Measure pressure when the tire is cold. That is before you do a trip.
That sticker is generic and not specific to the tires. Better to read the max PSI which is imprinted on the tires themselves. The sticker will say 35 even though the tires are probably rated 51.
I'm sorry but this is not correct. The sticker is not generic but instead is set by the manufacturer based on the car's characteristics (weight distribution, suspension, desired handling, etc) The max PSI is exactly that, a maximum upper limit of how much pressure the tire can take and is not specific to a car. If you think about it different cars can use the same size tires but the different cars have different characteristics, they require different tire pressures to produce the best performance.
But, the tire pressure recommended by the manufacturer is necessarily a compromise because they cannot know how you will drive the car (for example if you regularly drive by yourself or with the car completely occupied), however the manufacturer's recommendation is still a good starting point
See here for more information about choosing tire pressure and under/over inflation:
Tire Tech Information - Checking Tire Inflation Pressure
Tire Tech Information - Air Pressure - Correct, Underinflated and Overinflated
I'm no expert, not by a long shot - but that's not what I was told in these forums or by tire people. The tire manufacturer would not imprint a max PSI on the tires themselves if it were unsafe to use them at those pressures. They would imprint something like "see car manual" or they'd be getting sued day in and day out. I'm not advocating running your tires at 51, but the 35 on the C sticker is definitely a safe low and going higher isn't going to do any harm.
There are several other threads in this forum which discuss tire pressure. The OP should search for those threads which include comments from drivers much more experienced than I.
Pretty please, read the entire Owners Manual from front to back. There's a plethora of information that will instill a great chunk of wisdom that will help guide you with every car you drive for the foreseeable future.
Cars are complicated and dangerous machines with an ever-increasing number of electrical systems; it behooves you and everyone's safety to understand the basics before getting in the drivers seat. Our government has failed miserably in preparing us to competently drive an automobile [which is still a privilege, not a right]. We have to take it upon ourselves to be educated and experienced.
This is a misleading, and potentially dangerous attitude. The advocates of max PSI in your tyres never mention that the PSI number on the sidewall is accompanied by a max weight number - these two numbers must be considered together. Normally, your tyres will not be carrying anything like the max weight number. If you carry very heavy loads in your vehicle, then you should increase your PSI above the manufacturer's sticker value correspondingly. High PSI will decrease your tyre's contact patch with the road, and decrease your safety margin if not accompanied by greater weight. I have calculated that increasing my C's tyre pressure to 44PSI will reduce the tyre contact patch by about 27%.
Before you blindly pump your tyres to high pressures, get close up and personal with your tyres where they meet the road, and use your eyes and what's between your ears to see if there's enough air in them. If all the tread is flat on the road, and there is not a big bulge in the sidewall, then they are pretty right. Use a gauge to confirm and get them even. Brain first, gauge second. When I do this with my C I find that the sticker value for the rear tyres (29) is about right, but that I need to increase the front pressure from 32 to 38.
The vehicle and tyre companies have been in business for a century and employ professional engineers for their research and development. Forum opinion is often strongly held but seldom supported by evidence. I know who I trust more.
When I started driving I ran old Volkswagen Beetles for years. My tyres were regularly maintained to the sticker values and rotated, and I normally got 70,000 miles of even wear out of a set. If you want the most from your tyres, start with the manufacturer's values, and give them a little more, especially on a long trip.
Like I said, OP should search for the other threads concerning tire pressure.
Here are two of the other tire pressure threads:
Trouble Averted | PriusChat
Tire pressure question | PriusChat
Lots of C owners here are running their stock tires at 40 PSI or higher without issue.
My Prius C (4) came at 36 even from the dealership. I pump them up to 40 psi, the max wall figure on my tires Bridgetone Venza shows max 44 psi. I am getting about 4 more miles to the gallon and feels smooth. I wouldn't recommend going up to 44 unless you have 4 passengers and load on a long trip.
So this thread made me want to go check my tire pressure. What a pain in the rear to remove the valve cap. So I replaced the crappy plastic ones with these:
These are the double seal valve caps. No need to remove them. Just put the inflator or pressure gauge to it. easy.
At first, I thought they stuck out a bit too much, but I think it'll be fine.
no more getting my fingertips dirty. Just makes it very convenient to monitor tire pressure on a regular basis.
Oh man, I checked mine on the weekend and I was 27. I take it this could contribute to why I sometimes struggle to get 50mpg?
Tdog, welcome. You knew enough to come here & ask for advice so you know more than crap. There is a lot of good information here and I encourage a read through the topics of interest.
I use a digital tire pressure gauge from radio Shack. Tire pressure (tp) is a sore spot here. Please search for the many (and long) threads on this topic here.
An underinflated tire will contact the pavement on the edges, not in the center. The results are poor handling, hydroplaning, and excessive wear. Hydroplaning occurs when the tires lift off the pavement and ride on the water. You are now in a ballistic missle with no control.
When the entire tread of the tire is in contact with the pavement the tire is properly inflated. The results are good handling and even wear. The tires will last longer.
An overinflated tire makes contact only on the center.
Search for & read DRIVING UNDER PRESSURE.
A c is a great city car. Don't get freaked when you are stuck in traffic, the traction battery gets discharged and the gas engine (ICE) turns on...and off...and on... to recharge it. A little normal driving will bring the level right back up.
"Do you not have parents w/cars? Even I knew about tire pressures way before I could drive. My parents are NOT car enthusiasts either."
Cut the kid some slack. No, it is likely his parents don't have cars. Most city residents don't own cars or have driver licenses. They don't need them because they have bus & subway service. This may be like dropping me in Nebraska and expecting that I'd know how to use a combine.
Is the east side of the Financial District still flooded? I saw a photo of the lobby at 55 Water St. that looked like it had 4+ feet of water in it.