Pro Comp Series 51 Wheels, 15x8

[syndicate1]

While searching for new 15x8 wheels for my '74 with 31 x 10.5 tires and a WH Stock suspension, I came across the Pro Comp Series 51 wheels. Unlike most wheels with 3.75 backspacing and less than 30mm offset, the Pro Comp's are 3.75 backspacing and -44mm offset.

I used a wheel comparer online and it told me that the -44 offset would stick out as much as. 15x10 wheel with 4" backspacing and -43mm offset.

Does anyone have any pics of a 15x8 -44mm offset Pro Comp in their truck?

Is there any reason to not go with this whee?






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[DirtDonk]

Hey syndicate. Got a link to the wheels?
Where are you finding the specs? Any chance there could be misprints/typos?

You sometimes have to take offset numbers with a little grain of salt. I believe they can vary slightly due to wheel center design, and bead thickness.
Backspacing on the other hand is a fairly rigid spec that stays the same no matter what. Probably a slight variation with different beads, but there is not much leeway in a wheel bead due to them having to match the tires consistently.

So an 8" wheel with 3.75" backspacing is always going to have 3.75" of wheel inside of the mounting hub of the truck, and always going to have 4.25" of wheel sticking out from that mounting surface.
I don't see how that can vary. Especially by enough to make it act like a 10" wheel with only .25" more backspace.

I would go by the backspacing then. I could be wrong of course, but I just can't see how an wheel that's two inches narrower than another one, with the same backspacing, can stick out more than another wheel with the same backspacing.
Of course, the proof will be in the pics you asked for. Don't think I have any of Broncos with that wheel, but someone hopefully will.

You looked at any 7" wheels just in case? A 10.50 tire will work fine on either, so thought I'd mention it.
You running uncut, or with fender flares?

Paul

 

[syndicate1]

Im running cut fenders.

I found the wheels on Summit Racings website - https://www.summitracing.com/parts/pcw-51-5885/overview/

I then confirmed the specs by sorting the wheels on Pro Comps website - http://www.procompusa.com/wheels-landing-page.aspx?lc=PCW

Here is the wheel comparer that I used assuming a tire size 265/75/15 = 31x10.5x15 http://www.wheel-size.com/calc/

 

[DirtDonk]

Well I don't mean to dis Summit's website, but they didn't even get the weight rating of the wheels correct (1800 lbs vs the 1600 lbs listed by the manufacturer) so take the offset specs with a grain of salt even more.

Still no guarantee I'm right of course, but still pretty sure you can go strictly by the backspacing and get a wheel that will work with your truck.
An 8" wheel with 3.75" backspacing is pretty darn good (and very common) for an EB.

And a 265 mm tire should work just fine too.
Again, wait for others to chime in if they've a mind to, but that's my story and I'm stickin' to it.;D

Paul

 

[jwh]

Wouldn't the offset be directly related to the backspacing? Backspacing is from the back edge of the wheel to the mounting surface, and offset is from the center line of the wheel to the mounting surface. Or at least that's always how I understood it.

I've always understood it to be an 8" rim actually measures about 9" total width (the 8" is inside the lips, plus 1/2" each side for the actual lip). So using 4 1/2" (half rim width) - 3 3/4" back space = 3/4" from wheel CL to mounting surface = -19mm offset.

I really think the specs must be wrong. I just don't see how -44 offset and 3 3/4 backspacing would work together. A -44 offset with 3 3/4" backspacing would make the rim about 11" wide (44mm=1 3/4", so 1 3/4" offset + 3 3/4" backspace = 5 1/2" half wheel width)

I would figure out what you need for backspacing and stick to that number.