Proper tire pressure for 245/70/17 winters?
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CJ3Flyr
Super Moderator
At least 35 to support the weight of the T4R. You're allowed to use up to 44psi in the Blizzack. If it were mine I'd probably run 40-42psi. Let us know how they work for you.
How does one calculate that?
CJ3Flyr
Super Moderator
By studying charts like this: http://cache.toyotires.com/sites/default/files/loadinflationtable.pdf
The fact it's Toyo vs Bridgestone doesn't matter much. The rules are standardized for P-rated tires.
Your OE tires carry 2337lbs at 35psi. Toyota says use 32psi which equates to a load rating of about 2270. Because it's a P-tire on an SUV or truck you decrease the capacity by 10% yielding about 2050 (I'm doing this in my head, forgive the slight math errors). Your P245/70/17 Blizzacks have a capacity of 2205 at 35psi. Knock 10% off that and you're right back at the Toyota OE recommended 2000+/- of capacity.
:wtf: right? 35psi? On the side of the tire it says 2205@44psi
P-tires are weight rated at 35psi, period. Certain tires by certain manufacturers are deemed 'ok' to run as high as 44psi (or even 51psi) if the user chooses. It does not add load capacity to fill above 35psi. It does add stability at high speeds, resistance to hydroplaning, improved mpg and in the case of your tire size/rim width 38-40psi may be necessary to get the tire to wear evenly. Even at 35psi the edges may wear more than the center.
:cheers:
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I have been busy with calculating tire/tyre-pressure wiht use of the formula of the European ( ETRTO) wich is , so I discovered lately, other than the American TRA formula. this is the formula the European car-manufacturers also use to determine the advice pressures for on the plancard somewhere on the car mostly. For maximal load of the car ( Heavy load I call it) they use the Maximum permissable axle-loads and for the rear maximum of the tire mostly( I call that vacation use,and make the max axle loads 85% of the weight to calculate with. For normal use the car-manufacturer determines the axle-loads for 3 persons and a little lugage ( for cars with more persons mostly 4 persons).
I learned myself Excell to make spreadsheets for it, and the last ultimate spreadsheet is to calculate advice pressures for non-OEM tires. But can also be used to check your original tires.
http://cid-a526e0eee092e6dc.skydrive.live.com/browse.aspx/.Public/Recalculating tyre-pressure
In this map always take the newest version, and there are examples.
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