69 Dart tire size…

[DentalDart]

Lots of reading I’ve done with tire sizes and offset hangers/spring relocation to fit 275s in a 69 dart with stock tub and stock 8.75in rear end.

275/60/15 will fit with stock tub and 1/2in offset shackles or 3in spring relocation. But don’t do 3in spring relocation unless doing a mini tub because you don’t gain any extra space over the 1/2in shackles. Correct? To get the tires to fit you need a 15x8in wheel 5in offset or 5.25in offset wheel?

Now here is my dilemma. I want 275s because 245 isn’t enough tire and that’s all I can run on my other 69 dart with stock spring location.

I also want rear disc brakes, because I do not like the drums on my other 69. But disc brakes move the tires out an extra 1/2in correct?

So to get 275s on the 69 dart With Disc brakes, is it required to do the 3in spring relocation and mini tub? Or will I still be able to do the 1/2in shackles as long as I nail the wheel backspacing?

First photo is new dart other photos are purple dart with stock spring location, 245/60/15, SS springs, drum brakes. About 1/2in clearance on passenger side with rolled lip and 3/4-1in clearance on drivers side with rolled lip.

 

[sabre67]

subscribed

 

[72bluNblu]

There is no point in doing a 3" spring relocation without the mini-tub to go with it, correct. Even with only a 1/2" offset the inner fender becomes the limiting factor for tire width, not the springs.

275 is doable on a Dart, with a 1/2" spring offset and some work to the quarter lip.

Rear disk brakes do not add a 1/2" to the width, more like 3/16"- 1/4". Basically it's the width of the rotor sitting on the face of the axle vs the width of the drum where it mounts. It doesn't change the maximum tire size that will fit at all, it will just change the backspace needed on the wheel to make it fit.

Is this stock A-body 8 3/4 going to be running BBP or SBP axles? And this is not for the purple dart in the pictures, but a different one?

 

[DentalDart]

There is no point in doing a 3" spring relocation without the mini-tub to go with it, correct. Even with only a 1/2" offset the inner fender becomes the limiting factor for tire width, not the springs.

275 is doable on a Dart, with a 1/2" spring offset and some work to the quarter lip.

Rear disk brakes do not add a 1/2" to the width, more like 3/16"- 1/4". Basically it's the width of the rotor sitting on the face of the axle vs the width of the drum where it mounts. It doesn't change the maximum tire size that will fit at all, it will just change the backspace needed on the wheel to make it fit.

Is this stock A-body 8 3/4 going to be running BBP or SBP axles? And this is not for the purple dart in the pictures, but a different one?

It’s for my new 69 swinger, not the purple one, although I should do it on the purple one too. The new dart will have BBP axles and wheels. It will get SS springs or something like that, I stole the brand new SS springs off it and put them on the purple dart and I don’t mind the ride of the SS springs.

I thought I’ve read many times that discs in the rear adds 1/2in, but that’s good that it is less and can be compensated via backspacing.

I also don’t know what disc brakes I’ll run yet, right now it has stock 72+ disc brakes in the front and none in the rear.

 

[RustyRatRod]

33x21.50x15. Don't think about it. Just do it. lol

 

[mopowers]

To fit 275/60's in my '68 Dart sedan, I needed 15x8 wheels with a 4.75" BS. That was with a rearend built to A-body factory width. It's best to get your rearend in place and measure from there. With a 1/2" spring offset, there's not a lot of margin for error when it comes to backspace if you intend to run a 275/60/15 tire. It cane be done, but it's a little tight.

 

[RustyRatRod]

To fit 275/60's in my '68 Dart sedan, I needed 15x8 wheels with a 4.75" BS. That was with a rearend built to A-body factory width. It's best to get your rearend in place and measure from there. With a 1/2" spring offset, there's not a lot of margin for error when it comes to backspace if you intend to run a 275/60/15 tire. It cane be done, but it's a little tight.

View attachment 1716110556

Dammit that's a good lookin car!

 

[mopowers]

Dammit that's a good lookin car!

Thanks man. It's just a beater, but it cleans up alright.

 

[DentalDart]

33x21.50x15. Don't think about it. Just do it. lol

Is this the same size as the 275 lol.

 

[RustyRatRod]

Is this the same size as the 275 lol.

33 inches tall, 21.5 inches sidewall to sidewall on a 15" wheel. So.......no. lol

 

[DentalDart]

To fit 275/60's in my '68 Dart sedan, I needed 15x8 wheels with a 4.75" BS. That was with a rearend built to A-body factory width. It's best to get your rearend in place and measure from there. With a 1/2" spring offset, there's not a lot of margin for error when it comes to backspace if you intend to run a 275/60/15 tire. It cane be done, but it's a little tight.

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I’ve seen your car multiple times, part of what has helped me see it can be done, but I wasn’t sure if you had disc brakes or not. My 8.75 is an A body rear end with factory width.

You definitely have a good looking car. Right now I’m in the early stages…. Still fighting with myself on the color.

 

[DentalDart]

33 inches tall, 21.5 inches sidewall to sidewall on a 15" wheel. So.......no. lol

Don’t know the measurements it would come out to in the other sizing. Like my 325/65/18 comes out to just over a 35x12.5x18 on my truck.

 

[RustyRatRod]

Really? And you're a dentist?

It would look about like this. Probably a little bigger.

 

[DentalDart]

Really? And you're a dentist?

It would look about like this. Probably a little bigger.
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Im a damn good dentist too.

But no, off the top of my head I do not know what tire sizes come out to when converted.

Those are some massive tires! I’m good without that much tire, I wouldn’t even know what to do with that much tire.

 

[RustyRatRod]

Im a damn good dentist too.

But no, off the top of my head I do not know what tire sizes come out to when converted.

Those are some massive tires! I’m good without that much tire, I wouldn’t even know what to do with that much tire.

I believe it. I think you really are. But just look at the measurements. They're in inches dummy. You ain't THAT brainwashed into the metric system, are you?

 

[RustyRatRod]

Im a damn good dentist too.

But no, off the top of my head I do not know what tire sizes come out to when converted.

Those are some massive tires! I’m good without that much tire, I wouldn’t even know what to do with that much tire.

Well, you'd have to back half the car to get those under it anyway.

 

[mopowers]

I’ve seen your car multiple times, part of what has helped me see it can be done, but I wasn’t sure if you had disc brakes or not. My 8.75 is an A body rear end with factory width.

You definitely have a good looking car. Right now I’m in the early stages…. Still fighting with myself on the color.

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I should've clarified - when I said my rearend was built to factory width specs. With disks, I couldn't imagine the rotor adding much more that 1/8" to 3/16" per side over a drum. You really are better off hanging the rear and pulling some measurement. None of these cars are identical and tucking 275's in these little A-bodies gets pretty tight. I'm looking forward to seeing what you come up with.