Boy, I am really confused now!!!:confused:

My local Discount Tire salesman claims that his computer says that the Offset on the 2006 GMC 2500HD production OEM (http://www.dieselplace.com/forum/autolink.php?id=62&script=showthread&forumid=124) 16x6.5 Steel wheels is 29mm. But he also claims that he measured my OEM (http://www.dieselplace.com/forum/autolink.php?id=62&script=showthread&forumid=124) wheel and he says that the Backspace was 5.25" -- This does not compute.

My calculations tell me that for a 6.5" wide wheel
19mm Offset = 4.50" backspace and
38mm Offset = 5.25" backspace.

He also tells me that for 265/75R-16 tires with 16x8 wheels the offset should be between 0 and +29mm.

Does anyone have actual measurements for the OEM (http://www.dieselplace.com/forum/autolink.php?id=62&script=showthread&forumid=124) Steel wheels?

Thanks.

FYI, I believe that the 2500HD steel wheels are 6.5" wide but the 3500 SRW steel wheels (mine) are 7" wide. That might play into the 'puter...

Most the rims sold for our trucks do not have enough backspace. Be careful.

I don't know the offset on the oem wheels, but from the sticky above they are probably around 4.5-5.0. I don't think that they are as much as 5.25 because that would mean that the distance from the outside face of the wheel to the outer lip is only .75 inches (giving .5 inches for the mounting surface). I don't buy it. From looking at the wheel (no actual measurements taken), I'd say that a 4.5 inch backspacing is probably the case for our wheels (it apears our wheels have about 1.5 inches between the outside face and the lip of the wheel). If you are looking for new wheels, many people are running 16x8 with 4.5 inches of backspacing. Some people have complained of rubbing with 285 tires, but I don't think these people had the t-bars turned. I have seen others who are running 295's on 16x8's with 4.5 b/s. They had to adjust the t-bars and trim the fenders a bit. Eagle and Weld both offer wheels with larger backspacing if you desire, or you can grab some cheap H2 wheels off of ebay. Finally, if you are only looking for a 265 tire, you can run that safely on your stock wheels.

Well, today I decided to measure my OEM Chrome steel wheels.

Here is what I got:

Wheel Type: OEM Chrome-Clad Steel (2500HD)
Wheel Size: 16" x 6.5"
.Backspace: 4-7/8" (4.875")
. . Offset: 29 mm (1.14")

Does anyone have dimensions for the PY0 Aluminum wheels, or for the wheels on a 3500 SRW?

When I measured my stock 16 x 6.5" aluminum wheels, I got 4 7/8" backspacing as well........

When I measured my stock 16 x 6.5" aluminum wheels, I got 4 7/8" backspacing as well........Thank you.:)

This is very good information to have that will help determine how well a particular set of tires and wheels will fit our trucks.

Like McRat said, "(m)ost of the rims sold for our trucks do not have enough backspace." You very seldom find anything that comes even close to setting the tire in the middle inside the fender. If you are installing very wide tires, you will need to "push" them out there in order to clear the suspension, but in my case I'm more concerned with a good fit with as little trimming as possible for a relatively small incremental increase in size. I suppose wheel manufacturers must like the tires to stick way out, but that's not necessarily my desire.

This site HERE (http://www.rims-n-tires.com/rt_specs.jsp) is excellent for figuring out your starting point. Enter all the dimensions for your present tire & wheel, then compare to the new ones using various Offsets and Backspace. They have very good explanations about clearances, etc. It gives you a good idea how close your tire will be to the suspension and to fender components relative to the tires/wheels you are replacing.

Moderators,

Could we set up a sticky in this section containing OEM Wheel size information, so that members can make a better informed choice when upsizing their tires and wheels?

I can get it started with this info:

RPO:_______PY2__________PY0____________NZ7________ ___
Usage:_____2500HD (Std)__2500HD (Opt)___3500 SRW (Opt)
Descr:_____Chrome Steel__Polished Alum__Chrome Steel__
Size:______16"x6.5"______16"x6.5"_______16"x7.0"_____
Offset:____29 mm_________29 mm________________________
Backspace:_4-7/8" _______4-7/8"_______________________

Hopefully someone can fill in the Backspace and Offset for the optional NZ7 Chrome-Clad steel wheel for the 3500 SRW.

Thanks.