onegmtech

does anyone else out there have a 02 silverado crew cab with 4.10 gears and four wheel drive? i also have 285/75/16 tires. it had 265 when i got it. my gas mileage has steadily got worse. and it dont seem to pull as good as it used to. i was thinking about putting 245/75/16 factory tires back on it. the only mod it has is a k&n filter. i really do good to get 10 mpg. has any one used a programmer and it helped. thanks

bad2006z71

tune up. clean your air filter, maf sensor, plugs, wires, run seafoam through a tank of gas. a custom tune will help bring power and possible mpg.

BassinProf

In all likelyhood going to smaller tires won't get you much fuel economy, and it could even make it worse, as it will have the effect of lowering your gear ratio. Think about it, you will be moving your truck a shorter distance with each tire rotation so you will need to increase the RPMs to holdthe same speed as before.Ignoring the difference in the weight of the tire, a smaller tire should give youmore pulling power and less gas mileage.

It's a truck, what can you expect? I have an 06 2500 4X4 with 4.1 gears and it gets about 10.5 MPG. I recently added a 6" lift and35" tires and expected my mileage to go down the crapper but it didn't because adding the extra big tires had the same effect as increasing my gear ratio.

onegmtech

i know its a truck but a lot of guys are getting say they are getting 15 mpg out of the same truck on the highway!!! yes larger tires makes your gear ratio go from like 4.10 to 3.73 but what everyone is saying i have talked to around here when we discuss this they say by going to a lower rpm you are actually out of the power band for the 6.0 which you actually lose mileage because you are lugging the motor. when you say 33 ddidnt change mileage are you actually calculating or going off truck display because those are wrong. i work at a dealer and tell you first hand those are wrong.

BassinProf

You're right that the speedo will be wrong with a tire swap. I used a programmer to adjust the computer for the larger tire size. After doing that, I verified with a GPS that the speedo was accurate so I'm certain my mpg didn't go down much if at all with the35" tires. I'm assuming one reason for that is that the 6.0 liter with the 4.1 gears has enough extra power to make up for theextra rolling weight of the tires, and again in theorygoing to bigger tires meansbetter mileage due to less RPM to run a given speed. Regarding someone getting 15 mpg with that setup, I'd be really skeptical. Maybe with 3.7 gears, but as you know, the 4.1 gears really trash your mileage.

BassinProf

Also, I should mention that almost all my miles are on the highway, where big tires would affect mileage the least.

bad2006z71

word, your speedo is most likely off if youve never accounted for the 285's. i have a 1/2 ton Vortec max 6.0 with 4.10's and in the city i get anywhere from 12.5-13.5mpg with only a replacement flowmaster and K&N intake and stock 265's. cant wait to get my tune. the 6.0 wont notice going from a 245-265/285 size tire to much. the 6.0 is just hard on gas. i would first do a total tune up (if you havent already) then look into custom tunes by nelson performance or blackbear performance. blackbear has 2 advantages: 1. he is cheap about $200, 2. for a refundable deposit he can send you scan cables to see how your truck is running, not only does this give him the ability to give you a very accurate tune, but it can tell you if something is not running right.

bad2006z71

my DIC is about .5-1 mpg off of hand calculating. there is some merrit to a larger tire helping with gas mileage but there is not many tires that will help, most of the time when people go to larger tires, they are putting on more aggressive tires so there is more rolling resistance to the newer tire. plus most larger tires are heavier than stock crappy facotry tires. i hate the my 6.0 gets the mileage itdoes and i can only drive it once or twice a week. so until the chinese take us over and gas gets cheaper, the saturn is the daily driver LOL