73deltaguy

Hello folks!

I am the proud owner of a 1973 Oldsmobile Delta Royale 2Dr. It is sporting the 455.

It presently is sitting on 15" Cragar wheels that are pitted and have surface rust. Originally I didn't think they were that rough but upon closer inspection I realized that the work required to bring them back to snuff would be significant. So I decided I would invest in new ones.

So the combo I would like to go with is a 15x8 on the front with a 225/60/15 BFG T/A Radial. What the heck kinda back spacing do I need? Would that be an ok size of tire for the front?

The rear I would like to go with a 15x10 rim with a 265/50/15 BFG Radial T/A. I see that the back spacing on the ones from summit racing is 4.25". Would this combo work on the back of my Olds???

I would like to order this stuff tomorrow so if someone can shed some light I would really appreciate that!

joe_padavano

You need a wheel with near zero OFFSET. Backspacing is dependent on wheel width, whereas offset is independent of width. In rough terms, backspacing is slightly more than half the rim width plus the offset, so for zero offset the backspacing needs to be slightly more than half the width. That would be about 4.25" for an 8" wheel and about 5.25" for a 10" wheel.

Redog

I concur.

IDK what the offset is of my AR39's I just picked up, but they do sit a bit wide for my taste. I guess I'll measure when I get around to painting my drums/calipers which I have to do now

copper128

Just my opinion here, but unless you're lowering the car, those tire sizes you chose are going to be very short on a big car. Also, you don't need a 8" rim for a 225/60-15 tire. 7" is plenty.

I think a better combo would be a 225/70 front on a 7" rim and a 275/60 rear on a 8" rim. Those sizes will give you the overall diameter you need to fill the wheelwells on a Delta 88.

If you like the look of a short sidewall, you could look into 17 or 18" wheels, but it'll cost a lot more.

73deltaguy

Thanks for the reply man! Now that I look at it, I think you are right.

Originally I was going to put 18" boss wheels but after tossing the ideas around, I came back to the Cragars.

Now I just can't figure out what the bolt pattern is........5x5 or 5x4.75???

Anyone know for sure??? Also whether the lug is 1/2 or 7/16???

copper128

5x5 bolt pattern, 1/2" lugs.

73deltaguy

Wicked! I will order my stuff tomorrow. I take it the 275/60s will fit back there with no issues too.......

copper128

With a 15x8 wheel, you'll need a backspace of 4 to 4-1/2" then you'll be good to go with those 275's.

73deltaguy

Cool.....the wheels I am looking at have a 4.25" back space so that should be good!

Thanks for your help man!

abelish52d

I have a 1973 detla Royale it's has 455... what bolt pattern is?

MDchanic

Is 5" pattern.

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- Eric