new to me 07 questions

[Jerry Redtruck]

Hi, I used to be on this site way back when I bought my new 02 dually. Been through injectors and all the issues.
I decided I didnt need a dually anymore and found this 07 chevy crew cab short bed. First thing the fuel gauge was all the way down to E and the light was on so I headed to fill up and I could only squeeze in 21 gallons. Is this right? does this truck have a smaller tank? Could my gauge be bad? On my dually I could fit 28 to 30 gallons with the needle still above the empty line.
I also noticed after I had bought it that the wheels are 17 inch GMC. The sticker says stock should have been 16. I guess they are off a newer truck. Will this be a problem with running too big of tire? I need to change the tires to some aggressive all terrain type and may as well change the rims while I am at it if it is a problem.
How do I know if I got the locking rear end?
Previous owner claims 23 mpg. I dont really believe that after never being able to do better than 13.5 with the 02. But I am optimistic I will at least do better than the 13.5
I tried scanning through the manuals that came with it but couldnt find the answers, thanks if you are able to help me out. Jerry

[JohnC]

Yes, it's a smaller tank; 26 gallons, IIRC. I've never had the guts to run mine past where it took about 23 gallons.

Some trucks came with 17" wheels. The tires are probably lower profile so the same diameter.

23 mpg might be a little optimistic, but I can get about 21mpg at 65 mph on fairly level ground (east coast driving). YMMV...

[christophersond]

The short bed trucks have a 26 gallon capacity gas tank. Your owners manual should give you all the particulars, but the gas tanks on long bed trucks are larger. The 17" wheels were an option, but if you check it, the spare will be 16" (unless the previous owner replaced it). I agree with JohnC that 23 MPG may be a little optimistic, but that 21 MPG is more realistic. Toward this goal, using the cruise control will help.

Chris

[Jerry Redtruck]

thanks for the replies, I gleaned quite a bit from this site while searching for a truck, both back in late 01 and again on this search.

I realized I posted in wrong forum...please move if necessary

[Kennedy]

The best spec to use for tire size is revolutions per mile. If you can find the spec of your 17" tires and see how this compares to the OE tires (682) you can calculate speedo/odo error.

Most any single wheel Dmax should be capable of 20 mpg + but it takes some tuning PLUS the tire size/ride height and speed needs to be kept modest.

[Jerry Redtruck]

The best spec to use for tire size is revolutions per mile. If you can find the spec of your 17" tires and see how this compares to the OE tires (682) you can calculate speedo/odo error.

Most any single wheel Dmax should be capable of 20 mpg + but it takes some tuning PLUS the tire size/ride height and speed needs to be kept modest.


thanks for the repy. I had the mechanics install your fuel filter system on my 02 when the injectors went out. I will probably want to add one to this rig.
I found a tire calculaor on line and figured out if I go with 265/70-17 it would be the same outside dia as 265/75-16. This is one size bigger than stock. will that size be a fuel milage problem? I will be getting with you soon about some needs for the truck

[Kennedy]

Never trust a calculator for tire size. While it would seem that this should work, more often than not it will not. Tire mfg is quite an inexact science. Sure they can duplicate the same thing over and over, but getting the mold size perfect is easier said than done.

[Jerry Redtruck]

Never trust a calculator for tire size. While it would seem that this should work, more often than not it will not. Tire mfg is quite an inexact science. Sure they can duplicate the same thing over and over, but getting the mold size perfect is easier said than done.
I am always learning. I had never heard of a spec for Revs per mile before. I educated myself on your site while reading about your custom ecm's. The Toyo tires I am looking at have a rpm of 648

[87max]

Rolling resistance a factor also eg- aggressive mudders, softer compounds, air pressure.