I got new tires on my 98 about 1,000 miles ago. and my gas mileage has really been terrible, worse than before. i checked the pressure in them yesterday and they were all at 32lbs. that seems a little low to me. i used to run that in my car.

so how much should these trucks have in the tires? and if the weather makes a difference im in north carolina and at night its about 50-60, and 70s during the day. and my truck is a super cab, 4x4

 

Pressure number is on the side if the tire, depends on type of tire. Is the new tire the same size as the old one? Same height?

Are the new tires heavier or softer? When I replaced the OEM tires, I lost almost 1.5 mpg due to the tires being about 10 lbs each heavier.

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I'm not sure. The tires before were all different. The previous owner put some crap used tires on it and this is the first time this truck has seen New tires in god knows how long.

 

There is no way anyone can recommend what pressure to run without you telling us more on the tire. What tire is it? What is the max pressure listed on the sidewall? What is the size info on the sidewall? (P???/??r?? or LT???/??R??)? What is the load range? All this info is on the sidewall. Post it so we can recommend. Each LR tire is different. 32 might be okay for one, but dangerously low for another.

 

Not long ago, I drove my 02 F150Scab4x4 from Homestead, FL, where I was working to NC where my permanent residence is (800miles). I carefully checked my gas mileage to and from. I was home a week. I got just over 14 mpg, 14.4 is memory serves. While at home, I changed the plugs the first time (119kmiles) and pumped the tires up from 30 to 40 psig. It got 16.0 mpg going back. About 85% of the trip is interstate or turnpike with a 70mph limit and I had the cruise set on 80mph most of the time. I do have a superchip program. My tires are stock size Michelins, 265x70x17.

 

I agree with kingfish, more info is needed

mainly the max psi/load rating

think of it this way- the lower the psi the flatter the tire so the more surface contact, great for sand and the beach bad for the hwy

the more psi the less contact area great for hwy driving but too much psi and you take away from your stopping and rainy weather traction and also a harder ride
remember- are you towing/hualing - extra weight on the wheels also effects surface area of tires so make sure your tires are in the load range at max psi
the more weight the more psi

sometimes you just gotta try different psi settings and find what works for you with out exceeding max psi
the number of plys is the thickness of the tire- more plys results in a stiffer more durable tire for off road use but more weight for the engine to move

BTY- I have 6 ply trail tires with a 60 max psi running at 45 psi on my f150 mostly hwy driving with a smooth ride but can turn off onto a dirt trail and not notice a difference in handling