Weld Racing is telling me that the information that my wheel specs for '04 factory wheels are wrong.

Here is what I sent them:

7.5" wide rim
5.5 inch backspacing (+44 mm offset)
6 x 135 mm bolt pattern

I thought this applied to both the 17 and 18 inch Ford factory wheels.

Here is what I received from them, regarding the size of the OEM 18" rims.

"Factory 8 inch wheel at +44 has a 6.23” backspace.

Our 8.5 at 40mm has a 6.32” back space and they fit beautifully."


The 8.5 inch he refers to are in the EVO series. I'm in the process of finding out which EVO offerings are made in this size.

 

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Hi Zach,

Strange reply from Weld regarding the OEM measurements, as the engineering specs published by Ford clearly state ALL '04 F-150 OEM wheels are 7.5" in width and have an offset of +44mm (rounds to 1.732").

[Note: For those following the discussion, offset is the measurment from the centerline of the wheel to the mating surface. Offset can be negative (-) or positive (+). Backspacing is the measurement from the inner edge of the wheel to the mating surface.]

If you do the math to figure the OEM backspacing, the centerline of the wheel should measure 3.75" + 1.732" (offset) = 5.482", which when rounded, very nearly adds up to the oft mentioned 5.5" OEM backspacing measurement.

If you look at the numbers quoted to you by Weld for their 8.5" wheel, the numbers don't seem to math out for me on the backspacing. Assuming the centerline of an 8.5" wheel is 4.25" + 1.575" (40mm rounded) = 5.825" backspacing, which does not equate to the 6.32" backspacing figure quoted to you. If we assume (for the sake of this discussion) that a Ford 18" OEM wheel really measures (as Weld contends) 8" in width, then we have a 4.00" centerline + 1.732" offset = 5.732" backspacing, which is not the same as the 6.23" number given you.

Using my backspacing calculation (for Weld's 8.5" wheels) of 5.825" and subtracting the OEM 5.482", I arrive at a difference of .343". This would suggest to me, Weld's extra inch of rim width is divided between sticking out .657" further to the outside and .343" to the inside. Weld's quoted backspacing of 6.32" - (an OEM) 5.482" = .838" differential. This would put .162" to the outside and the .838" to the inside. From my personal observation of a set of 17 x 8.5" Weld Stone Crusher's (with 33 x 12.5" MT tires) mounted on an '04 F-150, they appeared to stick out further than .162", versus the OEM wheels.

It is early and I haven't had my coffee yet Zach, so I hope I didn't make an gross math errors here. But with the outboard shock mounting in the rear, caliper and suspension component clearance considerations in the front, as well as that funky OEM offset to deal with, I think you concerns are well founded. I know I would want to be darn sure custom wheels are going to fit right -- before throwing down the big bucks required for the top shelf parts. Keep us posted.

 

FoMoCoFoMe..... Thanks for the reply, the rep at Weld who sent me the e-mail stated they had measured a factory wheel from an '04 F150. Somewhere a mistake was made on their end.

I do have another question though. The '04 you saw with Stonecrushers and 33-12.50's leaves me puzzled. Those wheels are 1" wider than OEM, with a backspacing of 4.625, according to the Weld web site and yet they only stuck out .162" more than stock? Since you hadn't had that caffiene before writing your response, could it be the decimal point is in the wrong place?

Your point regarding the custom wheels is well taken, especially when dealing with a manufacturer who will make the wheels according to customers specs. So far, of the three custom wheel manufacturers I checked out, Budnik is leading the pack for my business. Whatever specs are submitted need to be as close as possible as I doubt one can simply return the wheels due to a miscalculation.

 

After checking at Weld's website I don't see a StoneCrusher listed in an 17 x 8.5", and I do recall the dealer add-on window sticker said Weld 17 x 8; so clearly my bad on posting that 8.5" dimension. Also missing from the Weld's spec, is a listing for a 6 x 135 bolt circle and backspacing specific to that pattern. As BrewMaster did talk to Weld to verify the existance of a 6 x 135 offering a while back, we (now) know the wheels are available. As I can't see Weld decreasing the factory backspacing by .875" over the OEM wheels for a .50" increase, my suspicion is that the backspacing on the 17 x 8" Weld wheel is greater than 4.625".

Sorry for not being clearer earlier, my but only point about the StoneCrushers I saw, was that they looked like they stuck out a bit further than the dimensions you were provided would have suggested. I should also add, it is hard to discern whether the visual appearance of the tires sticking out further (particularly in the front), is as much a function of the square shouldered MT profile, as it is an increase in wheel width and/or change in offset.