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Deputy Director, Region 3 PA (west)
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Discussion Starter · #61 ·
Your bolt pattern is 5 holes on a 4 3/4 inch diameter.
Also, check the diagram below and recheck your measurements. Unless your '78 is raised up in the rear, a 2.5-3.0 inch backspace, 8 inch wheel should not fit in the quarter panels of a 5th gen Camino.

Bill

and since the diagram isn't specific, Backspace is measured from the inside (axle side) of the wheel.
 

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Running Centerline Convo Pro's on my '65 El. 15x7 front, with 215-70-15 BFG T/A's and 3 3/8" backspacing. rear are 15x7.5 with 245-60-15 BFG T/A's and 5" backspacing
 

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Running Weld Rodlites 15x7F, 15x8R on my 83SS. 215-70-15's on the front are too tall (26.85") and they rub. Moving to 215-65-15's (26.0") on the front (which is also listed as the stock tire size for a Monte Carlo SS G body)
235-70-15's on the rear fit just fine with no issues.
(I have run 275-60-15's and even 295-50-15's on the rear with no issues)
 

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Awesome useful wheel calculator!!!

Here are two sites that I've found to be very helpful. If you know your original factory supplied tire and wheel sizes, you can easily compare that with any proposed tire and/or wheel sizes that you're considering..............Ken


http://www.rimsntires.com/specs.jsp?item=Wheel-Tire size comparer&sw1=225&ar1=60&bd1=15&rw1=7.0&et1=10&sw2=235&ar2=50&bd2=17&rw2=8.0&et2=11&text1=Old Front&text2=New Front

http://www.rimsntires.com/specs.jsp?item=Wheel-Tire size comparer&sw1=245&ar1=60&bd1=15&rw1=7.0&et1=10&sw2=255&ar2=45&bd2=17&rw2=8.0&et2=11&text1=Old Rear&text2=New Rear
Thank you so much Ken Rogers...this is perfect! I found at the back of this page where they have guaranteed fit tire and rim packages!
 

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15x8 with 245/60/15 in front?? please help

I haven't seen this question specifically answered or didn't look right maybe. I'm ordering 15x8 rally's with 4.25 backspacing. Whats the widest tire i can fit all around on my '81 elky, specifically the front??? Can I fit 245/60/15 on the front without rubbing, without any modifications?? Or should I play it safe and stick with 235/60/15??
 

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15x8 with 245/60/15 in front?? please help

Please help, I'm purchasing some 15x8 rally wheels with 4.25 backspacing for 81 caballero. I want to know to biggest tire I can fit on the front wheels with no modifications and no rubbing. I would like to try for 245/60/15. Can anybody tell me if this size would fit on my front wheels with no issues? or should I go for 235/60/15??
 

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Deputy Director, Region 3 PA (west)
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Discussion Starter · #67 ·
Based on my experience with my '87, I'd bet against 245's. As the first post of this thread details, 235/60 on an 8" wheel with 4" BS is all I could fit. The 4.25 BS may give you a little relief on the outside, but I'd bet you'll be rubbing the frame behind the wheels. I'd suggest maybe buying two 245's, try them on the front first and if they don't work, move them to the rear and buy two smaller tires for the front.

Bill
 

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I installed a set of 235/60-15 Cooper Cobras on 15x8 5x4.5, 4.75 +0 Cragar Ultralite wheels last week. They look great but front wheels do rub a little on the rear of the inner fender. I have the Eibach Pro-Kit coils dropping it 1" from stock and BMR control arms all around, had to add 1/4" spacers to keep wheel balance weights from hitting links. I'm anxious to see how the rubbing behaves after I replace my sloppy steering box or even if it goes away.
 

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Discussion Starter · #69 ·
I installed a set of 235/60-15 Cooper Cobras on 15x8 5x4.5, 4.75 +0 Cragar Ultralite wheels last week. They look great but front wheels do rub a little on the rear of the inner fender. I have the Eibach Pro-Kit coils dropping it 1" from stock and BMR control arms all around, had to add 1/4" spacers to keep wheel balance weights from hitting links. I'm anxious to see how the rubbing behaves after I replace my sloppy steering box or even if it goes away.
It likely won't make any difference, as the condition of the steering box, good or bad has no influence on the positioning of the wheels/tires.

Bill
 

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I am building a street / strip El Camino and will be using air shocks out back ,so i should be easily able to avoid any wheelwell contact in the back ,due the "tail up, nose down" 70's era stance .I also am not too concerned over tires sticking outward of the wheel well to some degree .That said , i have 15 x10" wide rims with 3.77 backspacing on the way , and a set of pretty damn wide 295/50 R15 (section width 295) Cooper Cobras. ,so the only possible issue i can forsee is contact inboard, like framerail. Using your chart info and my somewhat limited mental capacity i was unable to determine if i should go outside and ram my head into a tree for wasting money or not - Does anyone with perhaps more knowledge and ability than I see a fitment issue re: inboard interference ?
 

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Discussion Starter · #73 ·
My guess is it won't work.
The 295/50 Cobra is 1.2 in. wider than my 275/60 T/A's and your backspace is only .23 in. less. My math shows it would be almost 1/2 inch closer to the frame rail. I had less than 1/2 inch to the frame with my 275/60's at rest, so I don't think they will clear, especially with the little bit of flex in the control arm bushings. It would be good if you could mock 'em up first, but that may not be possible.

Bill
 

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My guess is it won't work.
The 295/50 Cobra is 1.2 in. wider than my 275/60 T/A's and your backspace is only .23 in. less. My math shows it would be almost 1/2 inch closer to the frame rail. I had less than 1/2 inch to the frame with my 275/60's at rest, so I don't think they will clear, especially with the little bit of flex in the control arm bushings. It would be good if you could mock 'em up first, but that may not be possible.

Bill
I already found some race quality 1" wide (thick) steel ring wheel spacers i can use if I have to, that would step the inside out an additional inch would should give me plenty of clearance .They are also vavailable in 1/4" , 1/2" , and 3/4" widths so i figure what i will do is slap the tires/rims on there when they come in , and then figure out how much additional room i need to make sure i clear frame rails under load , and then order accordingly ,I think that ought to work. I'll have a lot of tire hanging out of the rear wheelwells of course but that really doesnt bother me ,that is pretty much how we had them back in the 70's .Hopefully i can get away with the 1/2" or 3/4" spacer plates and not have to go the full inch. Thanks for your input though, it tells me in real life what i had suspected, it's too close to call, and likely too close to be safe without using the spacers, especially under hard load like dragstrip style launches so now i have a much better idea of what to be both prepared for and to look and check for. You the man!
 

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Considering the large number of tire / wheel fitment questions asked about 5th Gen Caminos, I decided to incorporate a number replies I had posted over the years into a single post in the effort to share my experiences over the years with fitting larger tires to my ‘87.
In 1978, when the new “A” body (later to be designated “G” body) cars were introduced, GM departed from tradition and moved the tires more outboard of the chassis than in previous models. It actually resulted in a large scale front wheel bearing recall in 1978, when a number of bearings failed due to the increased load. I mention this fact because it relates to the difficulty 5th gen owners often have in trying to fit a larger wheel and tire combination. Many other production and aftermarket wheels are designed with positive offset, meaning the hub mounting surface is outboard of the centerline of the wheel. Too much positive offset moves the tire inboard and causes clearance issues with frame rails and suspension parts.
This drawing explains the common terms used.



So what does this have to do with fitting tires to your El Camino?
I’ve been fortunate to have a good friend in the tire business, which gave me access to different wheel and tire sizes, so my ’87 is loaded with as much rubber as will comfortably fit in the wheelwells. Hopefully you can use the info I provide to find a good-fitting set of tires for yours.

Subject vehicle: 1987 El Camino Conquista
Ride height (distance from the wheel opening lip to the ground at the wheel center)
Front: 24 1/8” Rear 23 5/8”
Front tires: BFG T/A 235/60-15, 26.1” diameter , 9 ¾” section width
Front wheels: GM Corvette Rallys, 15 X 8”, 4” backspacing

Comments: I’m pushing the envelope with this combination. No clearance issues with suspension and no rubbing on the frame rails or the left inner fender. Slight rubbing on the right side has worn a slot in the plastic inner fender at the top of the wheel opening about 3” inboard of the fender lip when wheels are turned hard left. I also tried the same tire with a 15 X 7” wheel with 4 ¼” backspacing. The bead lip of the wheel contacted the upper control arm on both sides. A little bending of the upper control arm lip solved that issue, but the tire tread rubbed the frame rail before the wheels could be turned to full lock, effectively limiting my steering travel. Therefore, I consider 4 ¼” BS wheels to be unacceptable for my use. With a shorter or narrower tire, 4 ¼” may work.

Rear Tires: BFG T/A 275/60-15, 28 ½” diameter, 11” section width.
Rear wheels: GM Corvette Rallys, 15 X 8”, 4” backspacing

Comments: Again, I’m pushing the limits of clearance. There is 1/8” clearance between the tire outside sidewall and the lip of the wheel opening. When heavily loaded, a severe bump causes the sidewall to lightly rub. A little grinding or trimming could fix the problem, but since it’s so rare that the truck is loaded, I haven’t made the effort. Also on severe bump, the tread surface of the tire contacts a few ridges at the back of the inner fender. Contact is so light that the undercoat is rubbed clean, but no damage to either metal or rubber. Clearance between the inner tire sidewall and frame rail with a 4” BS wheel is ½” left side, 3/8” right.
Originally the rear wiring harness was located on the outside of the left side frame rail. Relocating it to the top of the frame rail moved it out of harm’s way. Given that my suspension links are stock rubber, a little “give’ is necessary, so I feel I’ve reached the limits in tire size.

Conclusion:
What I’ve posted here are my measurements on my near-stock’87 Camino. As the man says, your mileage may vary. 70’s and 80’s vehicles often have side-to-side dimensional variations, and things like specific ride heights, condition of body mounts and suspension bushings can also affect your results. Also, there’s an unrecognized and unpublished measurement that affects tire fit. For want of a better term, let’s call it “mounted tire backspacing” or "MTBS", a measurement between the hub mounting surface of the wheel and the widest point of the tire sidewall, which would be about 5¼” on my rears.
Most folks today are going for 16-20 inch wheels with 35 to 50 series tires, which have less sidewall bulge than my 15’s, so a 4½” BS, 9” to 9 1/2” wide wheel with a more straight-sidewall tire may fit fine, since the “MTBS" may very well be the same as my combination.
Two other points I’d like to address with folks inexperienced at radical tire and wheel changes. First, in order to maintain the original vehicle design parameters, I encourage you when replacing tires, to select a tire with an equal or greater load capacity than the O.E.M 205/75-14 tire, which was 1532 lb. capacity. I don’t care how large your wheels are or how wide your tires are. IMO, if you’re running a tire with less load capacity than the original issue tire, you’re flirting with danger. Secondly, wheel spacers are sometimes a necessary evil, but avoid them whenever possible. If you find spacers are necessary, use the absolute thinnest ones possible and make certain you have enough exposed thread on the wheel studs to engage the entire threaded portion of a lug nut.
Tires and wheels are an expensive modification. Before you write the check, spend some time on the tire and wheel mfr’s websites and know the dimensions of your proposed combination. Using my dimensions as a reference, you should be able to determine with reasonable certainty whether or not your combination will work.
I hope I haven’t bored you to sleep. Considering the high number of “will these fit?” posts on ECC, if my advice can help someone buy the right tire / wheel combination the first time, it was a worthwhile investment of my time.

Comments, replies and constructive criticism are welcome.

Bill
Great write up! I’m in the process of rebuilding a 1985 Caballero and I’m trying to order some wheels for it. My question is, the website says that the wheels won’t fit a 1985 Caballero or El Camino but it will fit a 1982 Chevrolet Malibu. I thought these g body cars were very similar when it comes to wheel sizes. Am I correct?
 

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Deputy Director, Region 3 PA (west)
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Discussion Starter · #76 ·
Great write up! I’m in the process of rebuilding a 1985 Caballero and I’m trying to order some wheels for it. My question is, the website says that the wheels won’t fit a 1985 Caballero or El Camino but it will fit a 1982 Chevrolet Malibu. I thought these g body cars were very similar when it comes to wheel sizes. Am I correct?
You're correct. All A/G bodies from '78 on use the same wheel style 14" with a 5 on 4.75" bolt circle.
In 1982, GM applied the A-body designation to the new line of midsize FWD cars, which are totally different in bolt circle and offset. The Chevrolet version was named Celebrity, as the legacy RWD Malibus were still being produced, hence the change from "A" to "G" in car line designation for the RWD platform. The Malibu name didn't reappear until 1997,

Bill
 
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