70 Dart maximum rear wheel size found

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dans4door1970

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Ok, mounted my new Vintique wheels, 15x8x4 with a 4 1/2 inch backspace on 245/60-15 Cooper Cobras and they fit fine and look awesome with my stock dog dish caps which also fit the Vintique wheels fine. I have superstock springs in the stock location but no alterations to the fender inside lip was needed. My axle was the same on both sides thank goodness.
Now for the opps! moment. I was so worried about the rears, I ordered 15x6x4 standard backspace for the fronts and ordered Cooper Cobra 215/70-15's. When I turned out of my shop, the front lip of fender hits them, so, I ordered 215/65-15's as I know they fit and turn fine. I wanted the height of the 70's. My Discount Tire dealer took care of me and will exchange for free. My bad. I could have went with 205-70's but Cooper doesn't make it in this tire. This made my sleeper complete yet aggressive in it's stance to the trained eye. Very happy and thanks for all the info.
 
Great tire and wheel info. Thanks. Do you have a pic? Hopefully I'll get tires on mine by this time next year.
 
Post some pics and I'll see if I can do a "sticky" so others will know. I used 15x7 with a 4.25 backspace and 255's and have extra tire to spring clearance. Little or no wheel lip room though. Thanks for the info.
 
toolmanmike said:
Post some pics and I'll see if I can do a "sticky" so others will know. I used 15x7 with a 4.25 backspace and 255's and have extra tire to spring clearance. Little or no wheel lip room though. Thanks for the info.
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255's are to wide for a stock fender, that's why I went to the 245's with a 4 1/2 inch backspace. the fender lip is close but clears the sidewall and my superstock springs are so stiff I don't worry about flex or soft suspension flexing
 
255's aren't too wide for all cars. 245's are a much safer bet for sure, but there are more than a couple members running 255's with the stock spring locations. It's an easier task if you're willing to do a little trimming on the quarter lip though.

As for the backspace needed, you have to be careful. The backspace needed for a stock SBP A-body 8 3/4 is different than an 8 3/4 that's been upgraded to BBP axles and brakes, the BBP axles make the track width a little over 5/16" wider on each side. It doesn't sound like much, but I wouldn't use a 15x8 with 4.5" of backspace with a BBP axle 8 3/4, I'd use more like 5" to 5.25". Even on a SBP car using 4.5" of backspace on a 15x8 puts you closer to the quarters than the springs, and really you want the extra clearance on the quarters.

And then there's the BBP 7.25 and 8.25" rear axles, which are totally different than either 8 3/4. They're over an inch narrower than a BBP 8 3/4.

A-body drum to drum measurements:

SBP 8-3/4: 57 1/8"
BBP 8-3/4: 57 13/16"
BBP 7.25/8.25: 56 11/16"
 
72bluNblu said:
255's aren't too wide for all cars. 245's are a much safer bet for sure, but there are more than a couple members running 255's with the stock spring locations. It's an easier task if you're willing to do a little trimming on the quarter lip though.

As for the backspace needed, you have to be careful. The backspace needed for a stock SBP A-body 8 3/4 is different than an 8 3/4 that's been upgraded to BBP axles and brakes, the BBP axles make the track width a little over 5/16" wider on each side. It doesn't sound like much, but I wouldn't use a 15x8 with 4.5" of backspace with a BBP axle 8 3/4, I'd use more like 5" to 5.25". Even on a SBP car using 4.5" of backspace on a 15x8 puts you closer to the quarters than the springs, and really you want the extra clearance on the quarters.

And then there's the BBP 7.25 and 8.25" rear axles, which are totally different than either 8 3/4. They're over an inch narrower than a BBP 8 3/4.

A-body drum to drum measurements:

SBP 8-3/4: 57 1/8"
BBP 8-3/4: 57 13/16"
BBP 7.25/8.25: 56 11/16"
Click to expand...
That's why I stated my car was stock except for springs. I didn't want to cut anything for tires that would fit. Why would anyone cut a fender lip for a 1/2 inch gain?? When I searched for a solution on this forum, I got what you just did, a bunch of maybe, if this and that but no yes or no simple answer. My post is for the driver who as me, just wants to upgrade with a bolt on solution without knowing all the combo's that won't work or all the things people have done to make it work. I appreciate your post for those who want to modify their cars. Since mine is a Grandma, special order car, I wanted to not chop it up. Thanks
 
Yes. And what I'm telling you is that the reason you got a bunch of "maybe's" and no "simple" answer is because not all of these cars are the same, even when they're 100% stock. Factory tolerances in the rear wheel wells frequently vary by as much as a 1/4" from one car to another, so, what fits one Dart won't necessarily fit another. There are members here that claim to be running 255's on uncut cars, and I can absolutely see how it would work just fine. A 255 typically has a section width of 10 to 10.2". For example, a BFG T/A in 255/60/15 has a section width of 10.2". But a Cooper Cobra 255/60/15 is listed as a section width of 10". On my '71 Dart there's 11" from the springs to the uncut, factory quarter lip on the passenger side, and 11 1/8" on the driver's side, everything 100% stock and uncut. What does that mean? It means I could clear 255's on the driver's side without rubbing, but maybe not on the passenger side. That's on the same car! It would come down to the tire manufacturer, because a 10" section width tire would clear fine, but a 10.2" might not. So I could run Cooper's without rubbing, but maybe not BFG T/A's. But on a car that had 11 1/8" on both sides? Well, with decent springs and/or a sway bar it would work fine, no cutting required.

Even little details change what will fit. The fact that you're running superstock springs can change how much clearance you have and how much you need, the car rides higher and the springs are stiffer so you can get away with more tire. Lower the car and that might not be the case. Add stiffer springs and a big sway bar and you can get away with having less clearance to the quarters because the body won't roll as much. A trip though the "post your wheel and tire combo" thread and you'll find guys with Darts that barely cleared 235's and one's that run 255's with no modifications. Just how it goes. And backspacing is critical for fitting tires like that, which is why I posted the differences in axle width's. The backspace needed for a SBP car and a BBP car are different. Sure, a BBP 8 3/4 isn't stock for an A-body, but plenty of people have them. And on a later car with a BBP 8.25" you need a completely different backspace than on a SBP 8 3/4, even with everything being stock and uncut those backspaces would be different by almost a 1/4" per side to put the same tire in the same place.

And yeah, I would do a little trimming on my car all day long for another 1/2" of tire. That's how I have 295's on the back of my Duster in the stock wheel tubs. Carry around some extra metal on the quarter lip that's outside of the spot welds and accomplishes nothing, or put extra rubber on the road where I can use it? Easy choice. Can't see it unless you stick your head in my wheel well. And there's too much tire in there to do that anyway. :p
 
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72bluNblu said:
Yes. And what I'm telling you is that the reason you got a bunch of "maybe's" and no "simple" answer is because not all of these cars are the same, even when they're 100% stock. Factory tolerances in the rear wheel wells frequently vary by as much as a 1/4" from one car to another, so, what fits one Dart won't necessarily fit another. There are members here that claim to be running 255's on uncut cars, and I can absolutely see how it would work just fine. A 255 typically has a section width of 10 to 10.2". For example, a BFG T/A in 255/60/15 has a section width of 10.2". But a Cooper Cobra 255/60/15 is listed as a section width of 10". On my '71 Dart there's 11" from the springs to the uncut, factory quarter lip on the passenger side, and 11 1/8" on the driver's side, everything 100% stock and uncut. What does that mean? It means I could clear 255's on the driver's side without rubbing, but maybe not on the passenger side. That's on the same car! It would come down to the tire manufacturer, because a 10" section width tire would clear fine, but a 10.2" might not. So I could run Cooper's without rubbing, but maybe not BFG T/A's. But on a car that had 11 1/8" on both sides? Well, with decent springs and/or a sway bar it would work fine, no cutting required.

Even little details change what will fit. The fact that you're running superstock springs can change how much clearance you have and how much you need, the car rides higher and the springs are stiffer so you can get away with more tire. Lower the car and that might not be the case. Add stiffer springs and a big sway bar and you can get away with having less clearance to the quarters because the body won't roll as much. A trip though the "post your wheel and tire combo" thread and you'll find guys with Darts that barely cleared 235's and one's that run 255's with no modifications. Just how it goes. And backspacing is critical for fitting tires like that, which is why I posted the differences in axle width's. The backspace needed for a SBP car and a BBP car are different. Sure, a BBP 8 3/4 isn't stock for an A-body, but plenty of people have them. And on a later car with a BBP 8.25" you need a completely different backspace than on a SBP 8 3/4, even with everything being stock and uncut those backspaces would be different by almost a 1/4" per side to put the same tire in the same place.

And yeah, I would do a little trimming on my car all day long for another 1/2" of tire. That's how I have 295's on the back of my Duster in the stock wheel tubs. Carry around some extra metal on the quarter lip that's outside of the spot welds and accomplishes nothing, or put extra rubber on the road where I can use it? Easy choice. Can't see it unless you stick your head in my wheel well. And there's too much tire in there to do that anyway. :p
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yep, to each his own. some people really want a simple answer and some cant give one 245's all day long!!!
 
Play nice!
As a FYI, I have seen the rear tire sidewalls running less than 1/8 to the spring, and have run nearly that tight myself.That's no biggie. But I needed at least 3/8inch to the inner tubwalls for spirited cornering. And about 1/2 to the outside. Rubbing on the smooth inside wall only slows me down a micro-second and does no serious tire damage. Getting into the outer lip on the otherhand, doesn't slow me down at all, but it sure tears up the tire!
-And I wouldn't run 245s on the back with any V8.Even a teener can roast those. And they have no traction when sliding; spinning you around in a heartbeat and putting you on the center divider.Well maybe not you,just me.But that is very embarrassing when it happens in traffic, not to mention dangerous.For occasional sliding 275 rears may work, if you be vewey,vewey cawefuul.But if you really enjoy it, you will need at least 295s. These finally have enough width to be controllable with the gas pedal as they are spinning and sliding in second gear at 40 plus mph, and the steering wheel is at or near full-lock.OK, maybe you didn't need to know that last part.
-And I trimmed my front fender corners in a heartbeat to put some sticky 245s in there.It wasn't even questioned.
But to be fair, good job on posting up, for the guys who need to know this stuff.
-And Blu has posted this stuff over and over and over,.....
 
AJ/FormS said:
Play nice!
As a FYI, I have seen the rear tire sidewalls running less than 1/8 to the spring, and have run nearly that tight myself.That's no biggie. But I needed at least 3/8inch to the inner tubwalls for spirited cornering. And about 1/2 to the outside. Rubbing on the smooth inside wall only slows me down a micro-second and does no serious tire damage. Getting into the outer lip on the otherhand, doesn't slow me down at all, but it sure tears up the tire!
-And I wouldn't run 245s on the back with any V8.Even a teener can roast those. And they have no traction when sliding; spinning you around in a heartbeat and putting you on the center divider.Well maybe not you,just me.But that is very embarrassing when it happens in traffic, not to mention dangerous.For occasional sliding 275 rears may work, if you be vewey,vewey cawefuul.But if you really enjoy it, you will need at least 295s. These finally have enough width to be controllable with the gas pedal as they are spinning and sliding in second gear at 40 plus mph, and the steering wheel is at or near full-lock.OK, maybe you didn't need to know that last part.
-And I trimmed my front fender corners in a heartbeat to put some sticky 245s in there.It wasn't even questioned.
But to be fair, good job on posting up, for the guys who need to know this stuff.
-And Blu has posted this stuff over and over and over,.....
Click to expand...
Golly, your so complicated. keep it simple
 
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