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Discussion Starter #1
Does anyone know what the widest tire you can fit in the back of a 69 12bolt... Backspacing,width, anything will help.. I didnt relocate my leafs or anything like that.. i think i could get 10.5 easy with the right wheel

Thanks for all replys.... They all will help
 

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Try doing a search you will get lots of info.
Most common size is a 275 tire on 9.5 rim with 5.5 backspace.
 

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Depends on the wheel size. A 15" wheel with a 275/60 15 is going to have bigger secion width then a 275/40 17. The taller profile will 'buldge' alot more.
 

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I've got a '69 coupe lowered 1-1/2" in the back with 15 x 8 minilites, 4-1/2" backspacing and 255/60/15's. That's max without any body or wheel well modifications unless (like Mark said) you go with a larger diameter wheel.
I have the exact same wheel size and spacing in the front with 235's.
 

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Disagree their guys, I have a 69 camaro 12 bolt, same specs 15x8 4 1/2 b.s. weld racing rims and BF Goodrich drag radial slicks, no mods what so ever and currently have the first set on right now, and look AWESOME car sits low tires tuck right in and still a little room left for more, Set at bottom i had when I bought the car, extemely slight rub sometimes on the right side, but they fit fine too! But, after going to the first set, they look SWEET!

1st set
Specifications:
* Tire size: P275/50R-15
* Overall diameter: 26.1 in.
* Section width: 11.3 in.
* Tread width: 10 in.
* Recommended rim width: 7 in. to 9.5 in.
* Load rating:1,830 lbs. at 44 psi

2nd set
Specifications:
* Tire size: P275/60R-15
* Overall diameter: 28.0 in.
* Section width: 11.1 in.
* Tread width: 8.8 in.
* Recommended rim width: 7.5 in. to 9.5 in.
* Load rating: 2,149 lbs. at 44 psi
 

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Pro - can you say 100% you can put 4 or 5 adults in your car and go around corners, through dips and in and out of driveways or any combination of the mentioned without any rubbing what so ever? I see all kinds of tire and wheel combos at cruise in and shows but the owners never load their cars and it takes them more time than most to get there as they have to drive around like they are in a glass car... Don't take this wrong, if you only intend to go straight and don't load up your car you can get away with more tire...

I ran 255/60/15's on 15x8 5"bs and rubbed, I ran 275/40/17's on 17x9.5 5.5bs and rubbed.

I run with 245/45/17's on the 17x9.5 5.5bs and can drive the car like I want with the whole family in the car and the trunk full...

255/60/15 - 10.2 sect 27.1 tall sidewall= 6.05"
275/40/17 - 10.9 sect 25.7 tall sidewall= 4.35"
255/45/17 - 10.0 sect 26.1 tall sidewall= 4.55"

A 275/50/15 sidewall= 5.55" with an 11.3 section width and a half inch less bs I would think there would be fender lip rubbing around corners unless the lip were rolled or trimmed. I didn't have a half inch to spare between the tire and fender lip with the 10.9" section 275/40's on a 5.5 bs 17" wheel.
 

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What about the front? How big there? 235 45 17 or 245 45 17?
 

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Procharged, wear do the 275/60 drag radials rub? Is it on the inner wheel house or the quarter panel lip, and do you have stock springs? I am currently changing my springs, and need to run a 275/60/15 to kill off some of my 4:10 gear ration on the highway, I am also hoping to get better than my current 2.2-2.4 60 second times.
thanks
 

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I just remembered this but the Pro-Touring site has a table set up over there that lists members rides tire and wheel spec's if you want to go over and check it out.

Say hello to Larry for me and say pdq67 sent you over if you do any chatting and such..

pdq67
 

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Sorry I was late on the reply! YES i guarantee it but cannot remember the last time I wanted even 3 ADULTs in the back of my CAMARO. So I would not worry about that part shoot they can take turns if they want a ride, or follow us? lol....you know what I'm saying....I have plenty of room left with 3 INCH EXHAUST Pipes coming out the back! STOCK rearend 12 bolt no mods, ssm traction bars shoot KZ came over and saw the car.
 

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First off i apologize because I'm no expert up front I am strictly talking about the rear! I don't run skinnies or anything like that, I just like a slightly skinner tire up front.


This set right here fits great with some room to spare, just watch your height on front because i'm guessing a little but i know my front tire is a 60R but because it's 215 i think 215/60r/15x6 the height is perfect for me.
1st set
Specifications:
* Tire size: P275/50R-15
* Overall diameter: 26.1 in.
* Section width: 11.3 in.
* Tread width: 10 in.
* Recommended rim width: 7 in. to 9.5 in.
* Load rating:1,830 lbs. at 44 psi

This set I have setting in my garage and they will only really rub slightly on hard turns with 2 adults in back on pasenger side and that is on outer lip.....personally this is your call, they were on the car when I bought them and ran fine, just a very tall tire to me.
2nd set
Specifications:
* Tire size: P275/60R-15
* Overall diameter: 28.0 in.
* Section width: 11.1 in.
* Tread width: 8.8 in.
* Recommended rim width: 7.5 in. to 9.5 in.
* Load rating: 2,149 lbs. at 44 psi
 

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web page


I was going to say DJD is looking at his car like I am so all I can maybe say is it's on a 17inch rim, as mine is a 15inch rim x8 and my tire is going to bulge in the rim which I like and understandable some do not. But this site up top helped me out in deciding on the tires I chose. And I was copletely worried when I ordered them through Discount tire, because I received no replys back on a earlier posting. Good to know, though, they fit perfect! Good luck!
 

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11.1" section width is closer to a 265.

section width in mm/profile ratio/rim diameter

265mm is ~11.041"
275mm is ~11.458"

if you have a tire labeled 275 and it has an 11.1" section width, it is labeled incorrectly.

just a FYI of course, i've been wrong before, and i s'pose tire manufacturers dont have to follow the laws of mathematics.
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question- isn't optimum rim size same as or larger than section width, so the sidewall is not overly ballooned? 7" rim sounds kinda small on an 11.3" section width, esp with a 10" tread width. i have a 255 on an 8 inch rim, and it looks a bit ballooned to me. not too bad tho'. i dont know the tread width, and can only assume the section width is 255mm, which is how it's labeled.
 

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Scott - What conversion factor did you use to convert 275mm to inches? I believe 275 = 10.826

Not every manufacture measures tires the same to come up with the designated size. For example a 275/40/17 on a 9.5" wheel measures...

Tread W - Sect W - Height
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10.6 ---- 11.02 --- 25.59 Per Nitto's web site
08.9 ---- 10.90 --- 25.70 (tirerack) g-force T/A KD
09.9 ---- 11.00 --- 25.70 (tirerack) dunlop SP Sport 9000

That's 1.7" in tread width and .12" in section width difference. The section width will change a bit to depending on wheel width... All 3 are close enough to 10.826" to be called 275's

On a bit different side of this thread the aspect ratio or sidewall height will determin handling characteristics. The taller, the more flex and the more flex the more likely to rub, especially when cornering. That is why I asked Pro about rubbing. There are many things that can effect this like rear end height. My car sits right about 12" center of hub to fender lip and may be about 1 1/2" - 2" lower than Pro's car with drag radials on it.
 

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thanks DjD. i had it mixed up. i was using 24, from memory, when it's really 25.4mm per inch.

something just didnt jive with me about having 2 different section width measurements on 2 tires with the same section width rating. so i crunched some #'s.

my point was the same tho'. the section width is the widest point of the tire. so i figured all 275mm tires should measure 275mm. as in, they should all be exactly 10.826", as advertised. not 281mm, not 287mm.

i did not take into account how it might change when mounted, depending on the rim and treadwidth, and sidewall stiffness of a particular tire affecting it. and probably the person doing the measurement as well.

thank you. you kind of answered my actual question too, besides showing me how little i know, but i'm still wondering why a 7" rim would be okay for a 275, and an 11" wasn't even on the list. wouldn't an 11" be better, so the sidewall doesn't ballooon? wouldn't it make for a stiffer sidewall, while a 7" rim would have it flopping around, so to speak?
i'm sure i read somewhere that the best rim is the same or slightly wider than the section width. was that BS? or maybe i read it wrong, and it was the tread width?
 

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I think tires will have an ideal wheel width set by the manufacture. It will be based on how the sidewall is constructed. From there you'll see acceptable width limits. 275/40/17's seem to all get sized on 9.5" wheels but usually manufactures will state they fit on 9" - 11" wheels. You might get them to mount on smaller than a 9" but it puts a stress on the sidewall as they are designed to be straight and stiff. The tire might roll off the bead of the wheels rim under hard cornering where it wouldn't if mounted on a 9" wheel. From there it goes the other way too. Too wide of a wheel and you may be driving on the sidewall when going straight. That means less traction and lowers the tires advertised performance...
 

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Discussion Starter #20
I would like to thank every1 for there imput it was great help.... I like that every type of rim combo was talked about... Thanks again
 
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