Ansen Sprints on a 70 Dart swinger

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Relax360

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I am getting my 70 dart swinger 340 up and running. I am getting Ansen Sprints from American racing. 15x7 4inch BS all the way around.

I was thinking 225/60R/15 in the front
245/60R/15 in the rear

Any tried this combo or will I have interference?

Brad
 
I think the front will need more backspace... 4.25 to 4.5 inches would be better... but every car is a bit different.
 
Do you have the stock 5x4” SBP, or have you converted to BBP?

If you’ve converted to BBP, no chance, you’ll have interference.

If you’re still SBP, maaayyybe. It’ll be pretty tight to the fenders and really tight to the quarters. Even with the SBP I’d say you’re firmly in the spot where some cars might pull it off, but some definitely won’t. That’s assuming you have an 8 3/4.

You’ll have to measure your car to be sure. You need to get your wheel mount to spring and wheel mount to quarter lip measurements. Tape measure and a carpenters square will work.

I’m just doing math based on my ‘71 Dart, but all of my measurements are based on the BBP set up and I’m doing more math to correct for the SBP offset differences. And the tolerances on these cars are more than enough to change things for you.
 
Yup SBP KH disc brakes. I realized I need 4.25 BS at least so I am looking for options now.
 
Relax360 said:
Yup SBP KH disc brakes. I realized I need 4.25 BS at least so I am looking for options now.
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Yeah in the front I think you could actually get away with the 4” backspace and 225’s. I ran 225/60/15’s on 15x7’s with a 4.25” backspace on my Duster, but that was BBP which adds more than a 1/4” per side.

In the back you’d need the 4.25” backspace to run 245’s. If you stepped down to 235’s it would work. But 245’s would be a crapshoot. Most cars would need the quarter lips trimmed/rolled to get enough clearance. At least based on the math.
 
Would the same hold true on a 68 Dart with SBP and K-H Brakes on front? Say 225-60-14 front and 245-60-14 rear? Sorry to but into conversation but my situation seemed so similar. Thank you, Brian
 
scampman said:
Would the same hold true on a 68 Dart with SBP and K-H Brakes on front? Say 225-60-14 front and 245-60-14 rear? Sorry to but into conversation but my situation seemed so similar. Thank you, Brian
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Basically, yes. Both SBP cars with KH brakes and 8 3/4” rears, so, same track widths.

But the 67-69 Darts tend to run a little tighter in the rear than the 70+ Darts. Not absolutely every car, but as a general trend the earlier cars had a bit less clearance to the quarters.

Even with the SBP offsets though that tire combination is so close it comes down to body tolerances, because the factory tolerances vary by more than a 1/4”. And a 1/4” will absolutely break you with that combo. So, you have to measure your car.
 
245s want an 8 inch to run flat to the road. If you put 'em on a 7 you will have to reduce your tire pressure drastically to get some decent tire life out of them. Maybe as low as 24psi. And when you do that it might corner kindof crappy, as the sidewall rolls under; it takes a bit of getting used to, as on the back, it will tend to oversteer the car.
Mathematically speaking,those tires should be about 9.65 inches thru the widest part of the sidewall, on a checking rim of 7 inches. That will tend to pull the outer edges of the tire, up off the pavement, at a standard pressure of about 30 psi. Which burns the centers off.
Just for reference;on the front of my 68Barracuda,I run 235/60-14s on 7s at 29 for tire life. The 235 really wants a bit wider, but I love my Sprints, and the 8.5s I got, are not gonna work. They do sorta work on 255s, But as blu pointed out there's no chance of making 8.5s and 255s work, on the front.
IMO the rim needs to be about .8 to .85 of the branded tire size. So a 235 would need 7.4 to 7.9 . And a 225 would need a 7 to 7.5. Taller profile tires can get away on the narrow end, while low-profiles need the widers. 60 series is sorta middle of the road to low-profile.
So at 7s you are pushing the envelope for 225/60s; IMO. So in your case I would recommend 4 same size tires so you can rotate them as needed, until you get your tire pressures dialed in. I recommend a starting point,with 225s,of no more than 28 in the fronts and 2 less in the back. Then keep your eye on the wears. In a DD, with pressures nearly correct, it takes about 2000 miles (or more) for a tire-pressure related wear pattern to develop.
Good luck!
 
AJ, Excellent information and a great description of everything I needed, what do you think about 225's on the front and 245's on the rear or just 235's on all four on 7" rims, can't thank enough for the help. You can PM me if you need to, Brian
 
Great info AJ thank you. At this piont I am considering doing a us car tool spring relocation kit to run a 15x8 in the back. Otherwise I think your call of 225/60 all the way around would be a wise choice.
 
Before you get too deep into that, I think it would be wise to mount the 7"wheel and measure to the fender lip. then compensate for the rim width, and bs, difference. I think you might find that an 8 incher with the common 3.75" backspace (giving a 5.25 front space,if you will;from the mounting flange to the outboard face of the wheel),will put the sidewall into the fender. I had to narrow my rear to the max to fit a 15 x 10 with a 4.5" bs. I think a 5" front space ,is about the max you can run on a stock width rearend. So it will be nip and tuck.
I had a 70 Swinger back when they were new, and I remember the mounting nightmares. I think I eventually did get an 8 on there, but it was a bit of a nightmare for an 18 year old kid. I just new those factory E70-14s had to go. E's were 7.35 treadwidth, not section, in those days.IDK the modern equivalent, perhaps 225mm. But the Gs that went onto those 8s, well, those were huge (lol) at 8.25inches tread, maybe 245/250. And of course the 340 smoked those as well, no surprise there! But to a grade eleven boy they sure looked racey.



Hang around for a bit, I'll bet 72 blu will pop in shortly for a more accurate update.If not, you might try PMing him.
Oh, I see blu already gave us the answer in post #5.
 
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235s on 7s will fit and turn, with the right bs
But you will have to reduce the tire pressure to run the treads flat to the pavement. 7s are about the minimum wheel width,8s would be better. The problem is that 235s want a 7.5 " rim using my .8/.85 rule and just try finding one.
I run 235/60-14s on the front of my 68 Barracuda. And on 7s. But at maximum 28/29psi for long treadlife.This does not corner very well. The tread rolls under, lifting the inside edge right off the pavement, and scrubbing the outboard sidewall, and the car does not go where you think it will. But if you pump them up, then the edges of the tires no longer touch the pavement, and when running in a straight-line, the centers of the treads burn up. Cornering on 32/34psi steers better, but now the grip is gone cuz you're only running on maybe 80% of the tire. So then you might as well have a tire that is proper for the rim.Airing up and down gets old after a while.
But when you put a 235 on an 8 then you can run the proper pressure, and things steer,run, and survive, better.
If you're just cruizing around, taking it easy, 28/29 feels pretty good, so if you're that type of guy, sure, by all means put the 235 on, and enjoy.
Otherwise, on 7s, I would run 225s, and no more. 225s want a 7 to 7.5 wheel.
As a rule of thumb, most any tire wants a rimwidth that is about the same as the treadwidth that touches the pavement, and as you probably know, the rim width, is measured between the bead seats.
 
Thanks AJ, as usual you come through. I am going to try to run the 235/60's on the 7" rims at 28 psi.
 
Relax360 said:
Great info AJ thank you. At this piont I am considering doing a us car tool spring relocation kit to run a 15x8 in the back. Otherwise I think your call of 225/60 all the way around would be a wise choice.
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You don't need a 3" relocation to run a 15x8. You can run a 15x8 with the stock spring locations, and probably use a 245 on most cars, but you need a 15x8 with the correct backspacing. Doing a spring offset doesn't change that, in fact, it puts all the extra space on the inside of the wheel well. Which means, you need to run MORE backspacing to take advantage of it.

As I said earlier, a 245/60/15 with a zero offset rim is marginal. It has been done by guys running the SBP 8 3/4, but not everyone has success. If you're willing to do some work on the quarter lips, you can probably make it work. Zero offset on a 15x8 would be a 4.5" backspace. Ideally, you'd want a 15x8 with a +6 offset, which is a 4.75" backspace for an 8" rim (or 4.25" for a 7" wide rim). Unfortunately, in 15x8" rims the 0 offset is usually about the best you can do in a lot of styles, at least off the shelf. Even the +6 offset or 4.75" backspace usually takes a custom order.

Also, if you're not planning on doing a mini-tub, there's no reason to do the 3" relocation. You can use a 1/2" spring hanger/shackle offset and get the same amount of room, because at that point the inner wheel tub will be the limiting factor. The 1/2" offset kit is a bolt in deal on the chassis, obviously you do need to move the spring perches on the axle in.

scampman said:
So would 235/60 on 14x7 cragars not work on my 68 dart or would that be pushing it?
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14x7" with a 4" backspace and SBP right?

The 235's should work in the back. In the front, it will be tight. By the math, if that combo were on a BBP front end it would stick out about .27" past the 275/35/18's on my car. Now, the change from SBP to BBP is more than that in offset, so, they should work. But, my fenders aren't in the stock location anymore. I pulled them a little when I installed them, and I've since rolled the lips and pushed them out further. Now, my car sits low, and that's most of why I did that. So, in the front I think it will work, but it will be close, and the lower your car is the more potential for rubbing you'll have.
 
72bluNblu, OK, from what I gather from your reply 235/60's on the rear and 225/60's on the front. I have to stay with the SBP because I cannot afford to do the BBP conversion, as far psi your suggestion, that would really help me. Thank you for taking the time to respond to my questions. Brian
 
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