I have the same tires on my 2000 with a 5.4. I run them at 45 psi always, and I have 10k miles on them with no tread-loss. They do seem to perform better on-road at 45 then at around 35. I say "perform" as in fuel economy, and how well the vehicle seems to handle. Just my experience, but it's worth a shot as they should handle at-least 50 psi no problem. Good luck.

- Erik

 

I really don't think my truck has been regeared---but what do I know. I don't know what the 2 previous owners did to it. Secondly, most of you will remember I kinda complained that it didn't have the "get-up-and-go" that my 05 Yukon 5.3 3.73 gears had. The 5.4 has gobs more torque than the 5.3 according to the specs...but that Yukon would launch off the line. And I'm talking about normal acceleration too...not hot doggin it....granted you'd be impressed that a 6000lb truck could move like that if you did.

My SCREW HAS gotten a lot better in that Dept. Its not up to the level of my 2wd Yukon...but i blame that on the GEARS! I just dont know how a 5.3 with 3.73 gears and slightly heavier truck got better gas mileage than my SCREW 4Wd with 3.55 gears. I know I have 2 tags on my rear diff.........one on each side. I'll have to see what they say or have ya'll decode them.

My BFG ATs are a LT tire with Load C if memory serves correct. I'm POSITIVE it says 50 PSI MAX on side wall. I'll pump 'em up to 45 PSI and try that---DirtySCREW

 

Running the rpm's you said it does at those speeds, it has not been re geared. If you access have a gps, just put it in there for awhile and compare the speeds, to check to see if the speedo is right.

 

minimize your idling. 30 seconds to a minute max. don't do drive throughs, don't warm it up. when I leave for work I don't let it idle more than a minute or two tops. when I leave work is a different story but I am out in the cold all night. don't take your tach above 2000 rpms. In the summer with my truck, full bolt ons 33's 3.73 gears, I get 22-24mpg at 50-55mph and 15-17 at ~80mph. and yes your dirty air filter can lose you 2-3mpg easy.

 

See Gotts....THATs what I'm takling about. I'm not trying to make a homemade rocket that can go to the moon (something pretty much impossible); I'm trying to get my truck to the level YOURS is at!!!!!! I'll keep at it even though I'm disappointed and keep ya'll updated.-------DirtySCREW

 

If the tires say 50 on them, put 50 in them for best gas mileage. They will ride terrible.

 

p rated tires are a lot different than LT tires. trust me I tried telling my dad this and the centres of his tires wore right out when he had 70psi in his (80 max). Mine are rated for 80psi max and run them at 50

 

I'm gonna go with what someone else referenced to before.. I had excellent luck in gas mileage with getting a bed cover. I went from an average of about 15.6 on the highway to 19 mpg when i drove to Maine with my girlfriend and son with the bed full of crap. Of course it was all highway but it definitely made a difference. I'm running an 07' FX4 w/ 3.55