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The other day I took a BFG AT into Discount Tire in Lubbock, TX to get it fixed. They ended up replacing the tire, and bumped all 4 wheels up to 35psi. I asked why they did 35psi when the door sticker says 29/26 f/r, and they said that
Discount Tire said:
since the BFG AT is a 6 ply tire instead of a 4 ply tire, it is heavier. Heavier tires like that need to run higher pressure to ride and wear correctly.
When I first got the tires, I thought that they were running a bit rough, and checked them after driving a mile or two. Turns out they had been put at about 55psi apiece. I lowered them, and haven't trusted Discount with tire pressure since.

So, I guess the question is this: Do heavier tires require more pressure like they said? Thats about 23%/35% f/r over the recommended pressure, which seems like quite a bit; however, on the other hand, the guy's argument makes at least some sense to me. Is this guy correct, or is he off his rocker?
 

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Going John Galt
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leecbaker said:
The other day I took a BFG AT into Discount Tire in Lubbock, TX to get it fixed. They ended up replacing the tire, and bumped all 4 wheels up to 35psi. I asked why they did 35psi when the door sticker says 29/26 f/r, and they said that

When I first got the tires, I thought that they were running a bit rough, and checked them after driving a mile or two. Turns out they had been put at about 55psi apiece. I lowered them, and haven't trusted Discount with tire pressure since.

So, I guess the question is this: Do heavier tires require more pressure like they said? Thats about 23%/35% f/r over the recommended pressure, which seems like quite a bit; however, on the other hand, the guy's argument makes at least some sense to me. Is this guy correct, or is he off his rocker?
their argument makes sense for those tires if you have a full-size rig that weighs another 1000# ;)
the book specs for tire pressure are for the OE street tires that come on the truck. Once you go to an off-road tire you can forget those #s for the most part. But, they are pretty darn close as far a guidlines go. Bigger off-road tires typically run lower psi on our light weight Tacomas than the tire mfgs suggest. Rim width will also determine psi needed to an extent, (OE 7" vs aftermarket 8", for example) with the wider rims allowing for more psi.

If, with 35psi, your ATs still have a nice flat contact patch (search "chalk test") with the pavement then keep them there. If, however, you look at them and the edges are off the street then they have too much air and the centers will wear out. Unless you carry a load on a regular basis our rears will always need to be at a lower psi than the fronts.

w/o the winch/bumper I used to run 28f/26r with my BFG Mts. With all the extra weight up front now I can run 32-35f/28r and only add more air if I'm hauling weight.

run the highest psi you can and still maintain a full contact patch for optimum gas mileage and handling characteristics.
 

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what the guy at discount tire said has some weight to it. but your tire pressure has more to do with the vehicle than with the tire its self. i have KOs on my truck, and when i got them installed i felt that i needed to increase my air pressure on all tires to 32psi. all my tires are wearing normal. i have always thought that tacomas start their life with not enough air pressure in general. when i used to install tires i found that most of the tacomas that came in had under-inflation wear. it is your vehicle, if they are doing something that you dont want them to do, tell them to change it. plus if you have a load range C tire, the MAX air pressure is 50psi. i would go to a different shop if you are having problems with that one.
 

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what the Discount told you is fucking stupid........think about it for a second.......if the tires have two extra plies then they will be stiffer......they also have a higher load rating........meaning that they will hold the same weight as your old tires with LESS air pressure.
 

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Full_Tilt_Fud said:
what the Discount told you is fucking stupid........think about it for a second.......if the tires have two extra plies then they will be stiffer......they also have a higher load rating........meaning that they will hold the same weight as your old tires with LESS air pressure.
This is exactly what I've found with my load range E tires. I told a service rep at the local Discount Tire that I had to run no more than about 26 PSI front/24 rear to get the tread to lay flat after he told me that tires like mine should be inflated more than normal.
 

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i wouldnt call it "fucking stupid" but in a tacomas case it really doesnt need to be discussed. when i was installing tires i remember reading something where michelin said that with added load capibilites ie higher load range, the air pressure should be increased. where as i would have discussed if someone would have wanted to increase their tire pressure, i would not have pushed them to increse it.
 

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NorCal Chapter Pres
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I dont even trust the door sticker. On my Dmax work truck, it says 50 on the front tire pressure. So I filled it to 50 and what do I get? A severly underinflated tire (the sides wore out QUICK in just 5000 miles... Note this is rolling right off the factory floor.

So after doing the chaulk test, I found that I need almost 75psi in the front to get full tread contact, and about 79 in the rear.

Screw the door sticker, I'll stick with the chaulk test.
 
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