Ouch... Wheels don't fit...

[BBC71Nova]

I'm slowly starting to appreciate the value in paying someone to just build the car and deliver it. True, the actual time/labor is part of it. The most value has to be with not having to deal with all the stress and frustration of stuff not fitting.

So I got my wheels in this week. Very nice. Only one problem. I just mocked them up and THEY DON'T FIT! . I had thought and was led to believe that using a wheel with known size and backspace was best method of determining what size new wheels to get.

I have a set of 15" X 10" wheels with tires mounted. The wheel is listed as a 5" backspace wheel. That setup fits fine but could stand to be 1/8" further inboard. With the new setup I went with an 18" X 11" wheel. Simple, right. Split the 1" difference in width yielding 5.5" backspace plus the extra 1/8" and voila new wheel needs to have 5 5/8th backspace to fit perfectly. NOPE. Apparently not.

So Either Weld or Vintage one measures wheels differently. From what I can tell the Weld wheel backspace is taken from the inner bead seat. The Vintage wheel is from wheel edge. The bead lip is ~1/2" and that roughly matches how much I'm off.

Fail! No telling how much this is gonna cost. There's gonna be a Nova bonfire before long.

OK I'm done venting

EDIT: more details later in the thread. Both Weld and everyone else does measure the same as you'd expect. After taking better measurements the variance in the Weld wheel is only 1/8" yielding 5.125 actual backspace. Probably considered within tolerance. Wheels spec'd out as planned aside from that. Just that after mounting I can see clearly that an additional .25" backspace would be ideal. Lessons learned: 1. Take actual measurements of the wheel you are using instead of trusting published specs, 2. within reason error on the side of more backspace since you can space them out later if necessary.

[Rick D]

Sorry that stinks but that's why you need to measure measure measure before you order wheels as no two cars are the same and there is always differences in wheel makers. What about rolling the lips on the qtrs???

[BBC71Nova]

Yeah that's the real suck part. I measured many many times and had multiple calls to make sure the logic with sizing was correct. Wow, that really worked out huh.

I knew a wheel edge to edge would measure wider than listed, e.g. 11" wheel is actually 12" wide. So it didn't seem too far fetched to think that the 1/2" difference in measured edge to pad backspace dimension was simply because it was also supposed to be measured from the inner bead seat.

I've had 2 sets of Weld wheels over the years in both 15x10 and 15x8 sizes. They both measured larger than listed backspace if you measured from the wheel lip to the pad.

Unfortunately the wheel lips were already trimmed so there's no answer other than new wheels I'm afraid.

[Ron in SoCal]

Man I feel for you John! To the best of my knowledge, there is only one way to measure backspace. Lay the wheel face down, put a straight edge over the barrel and measure from the pad up. Dave from Forgeline has a nice vid on the 48hour Camaro site:



If I'm in your shoes and the BS doesn't match what I ordered using that method I'd be all over the vendor.

Good luck and hang in there!

[214Chevy]

Originally Posted by Ron in SoCal

..... there is only one way to measure backspace. Lay the wheel face down, put a straight edge over the barrel and measure from the pad up.

That's how I did it when I ordered my HRE's. I was scared to death because I had never done it before and with paying that amount of money for a set of wheels had me very, very nervous. Nonetheless, doing it that way had me spot on and everything fitted perfectly. I hope everything works out for you.

[BBC71Nova]

Yeah Ron, from what I can tell after researching more is that Vintage is using the method of going from the lip to the pad. That measurement is spot on the 5 5/8" we spec'd out.

The flaw in the logic was with using the Weld wheel with 5" backspace as a point of reference. That wheel measures more like 5.5" using the lip to pad measurement. Funny since Weld doesn't even sell a 5.5" backspace 15" X 10" Alumastar 2.0 wheel. Clearly this is the problem.

I'll talk to Vintage tomorrow and see what the options are.

[FETorino]

Originally Posted by BBC71Nova

THEY DON'T FIT! . I had thought and was led to believe that using a wheel with known size and backspace was best method of determining what size new wheels to get.

I have a set of 15" X 10" wheels with tires mounted. The wheel is listed as a 5" backspace wheel. That setup fits fine but could stand to be 1/8" further inboard.

With the new setup I went with an 18" X 11" wheel. Simple, right. Split the 1" difference in width yielding 5.5" backspace plus the extra 1/8" and voila new wheel needs to have 5 5/8th backspace to fit perfectly. NOPE. Apparently not.

I'm not sure I follow your logic here. If 5" bs is fine but it could be 1/8" more inboard then you want 5.125" bs. If you go from a 10 to an 11" width the BS doesn't change you still have only the 5.125" to work with inboard. The question is with the 10" wheel did you have the extra .875" outboard to allow for the wider width wheel? You didn't say but from your measurements I would guarantee that the wheel is hitting the tubs cuz you have .5" to much BS.

[BBC71Nova]

Originally Posted by FETorino

I'm not sure I follow your logic here. If 5" bs is fine but it could be 1/8" more inboard then you want 5.125" bs. If you go from a 10 to an 11" width the BS doesn't change you still have only the 5.125" to work with inboard. The question is with the 10" wheel did you have the extra .875" outboard to allow for the wider width wheel? You didn't say but from your measurements I would guarantee that the wheel is hitting the tubs cuz you have .5" to much BS.

Sorry if it is confusing. I should have mentioned the tire differences. The current tires I have are 325/50-15 at 13.1" wide. Even with the wider 11" wheel the new wheel/tire combo will be narrower at ~12.5". To maintain the same relative tire/wheel positioning in the wheel tub you just take the extra inch and apply it evenly to both sides of the centerline. So that would be 5.5" BS. Then the extra .125" makes is 5.625.

As it stands now I have about 1.5-2" clearance between this wheel and the inner wheel tub. The problem is the wheel is too far outboard and thus the tire will be into the outer wheelhouse. The 1/2" extra BS would center it up. So I need ~6.125" backspace I guess.

[skatinjay27]

so john why didnt you go by the the actual measurement on the weld wheel and not the stamped number?

[Vince@Meanstreets]

no matter what you did or where you did it, its done. Hope they can take it back. Most rim makers are ok as long as you didn't mount a tire on it.