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K

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I have to ask this because I am always confused about tire pressure. We just put the Blizzaks on the car. Max tire pressure on them is 44 psi. I look in the RAV4 owners guide and recommended cold is 29 psi. In my other cars, I have always gone for a sort of healthy medium (or so I thought) and would go somewhere in between. Like I'm thinking 34 or 35 psi in this case. I ended up putting 30 psi in the cold tires last night. I want a psi that will give me decent gas mileage, but not go against what the tires are designed for. I have this fear that this could be a religious topic like some other automotive subjects...

Kathy
 

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Always keep them close to the vehicle manufacturer's listed tire pressure. When a manufacturer such as Toyota calculates the proper tire pressure, they take into account fuel economy, ride comfort, handling, and tire wear, and come up with a pressure that is a good compromise between all four aspects.

For the stock tire size, 30 psi is a good pressure. You can go a few pounds over 29 psi, but don't go under it. I keep mine at 32 because it makes the handling a little stiffer, and may increase my fuel economy a little. If you go more than a few pounds higher (or lower) than the recommended pressure, the tires will wear unevenly, and braking/handling will be adversely affected. 35 psi may be a little high considering the softer compound of a winter tire.
 

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Generally the guidlines set by the manufacturer are what you want to go by. It says 29 PSI, so you should only put 29~30 PSI in your tires when cold.

That being said, it is possible that some more air pressure could give a slight increase in gas mileage. Theoretically, the harder a tire is, the easier it is to roll. If the tire rolls easier, then the engine has to do less work to get it to roll therefore you may get an increase in mileage. I've never tried it, and I doubt that it would be easily measurable anyway. But please do not go out and max out your tire pressure. There is no reason to do this and would give an unneedingly harsh ride, not to mention increase the risk of blow outs.

The idea behind tire pressure is safety. The tire pressure rating is there because Toyota determined that with the weight of the vehicle and stock tire size, xxx psi will give the best contact patch.

If you've ever seen worn tires that were either over or underinflates you'll know what I mean. When a tire is over inflated, the center of the tire will wear faster. When underinflated, the shoulders wear faster. This is due to the relative contact patch of the tire ( the amount of rubber meeting the road). In either case, over or underinflated, you're not using the tire to its best capabilities for normal street driving as well as causing uneven wear.

If you want to know if the listed tire pressure rating is working, there are different ways to test your tires contact patch that I've read about but never bothered trying.

To test on your tires you can get chalk. Place a stripe of chalk across all 4 tire treads. Then drive the vehicle 1 revolution or so of the tire rotation on concrete or clean asphault. In theory the chalk that comes in contact with the ground should come off showing what part of your tread is making contact. Like I said never tried it, so don't know how well that works.

Generally I will check tire pressure about every week or two to make sure its about as consistant as possible. Then I'll check the tread wear after about 3,000 miles during an oil change. I can get an idea then to know if i'm on target and usually if I follow the manufacturers recommendations everythings ok.

So long explanation short, stick with the mfg. suggestions, they've thought about that number much longer than any of us have :!:
 

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Kathy a digital tire gauge is nice to have if you have'nt already got one. Just wait until they are on special.
Oh, i forgot you are an impulse buyer :lol: ...... :p
Anyhow, they are very accurate and simple to use. Just don't get the model with a very small LCD screen.. Remember to check the tires once a month along with a visual inspection.
Your neighbors will think you are a pro :D

Walt
 

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I recently pumped mine up to 38psi... bad move really... made the interior rattle so I'll take it back down to 34 where it felt OK there.
 
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I actually do check my tire pressure quite often, but have never used a digital meter. I'll definitely check them out... and take my time about buying it. I do have it in me to comparison shop....somtimes. :lol: I called the Tire Rack and they repeated what you guys are all telling me. Keep it around what the vehicle manufacturer says. So I'll probably stick with 30 psi and see how it goes. I have to remember I'm not driving my VW GTI anymore with Yokohama performance tires!

Kathy
 

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adamdirtP: Wow! You explain stuff really really well. The wording is very clear. Sometimes i have trouble describing things, and you've done a great job....especially the part where you talk about why higher tire pressure can improve gas mileage.
 

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Yeah! What he said. .....Sleeping all day again. Weird shift at work...... at least Kathy didn't spend a small fortune this time!!! :lol: :lol:

Keep it at Mfgrs. (Toyota) recommended presure!!!! Very important. Later. M.
 

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I agree, Adamdirt did do a nice job of providing a clear and simple explanation.

As mentioned in an earlier post, depending on your objectives, arguments can be made for adding more or less tire pressure than what is recommended. OEM manufacturers (and vendors like TireRack) tend to provide advice based on maximizing safety (and minimizing their liability) verses optimizing handling, longevity, or performance, etc.
 

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Thanks for the complements. Glad that I could explain it in a way everyone could understand easily.
 
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