I just purchased a 71 Demon project and I am at the wheels and tires time. I love the look of this Demon's 17" wheels, I have looked up on here the controversial 17" will fit and will not fit back and forth. Does anyone know what wheels these are? Also if anyone else on here know whats a perfect 17" wheel and tire combo with backspacing that would be greatly appreciated
1971 Demon 17" Help
- Thread starter J.B.
- Start date
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Those look like the modern rallye wheels that were produced in 17" sizes. Looks like you have about as big as you can go without scrubbing.
17x8 with 4.5 on the rear and 17x7 with 4.25 backspace on the front should clear. Others more knowledgable than me will chime in.
17x8 with 4.5 on the rear and 17x7 with 4.25 backspace on the front should clear. Others more knowledgable than me will chime in.
Probably these.
17 X 8 Cast Aluminum Mopar Rallye Wheel Kit
17 X 8 Cast Aluminum Mopar Rallye Wheel Kit
Yeah those appear to be the Year One 17x8's with a 4.5" backspace. They work fine in the back if you're running an A-body 8 3/4 with BBP axles, but in the front the 17x8 with a 4.5" backspace really doesn't have enough backspace. In order to put any decent sized tire on a 17x8 in the front you really need at least 5" of backspace, and really more like 5.25" to 5.6" is ideal.
Just for comparisons sake, a 17x8 with a 4.5" backspace and a 225/50/17 on it (narrowest tire recommended for a 17x8") your tires would stick out further than the 275/35/18's I run on 18x9's on my Duster. Can they work? Yeah, if you run your ride height high enough they probably won't rub. But if you lower the car from stock at all they'll interfere with street driving. Technically a 215/50/17 would put the tire in the same spot as my 275's, but the widest rim recommended for that tire is a 17x7.5", and those Year One rallies only come in 17x8 or 17x9.
Just for comparisons sake, a 17x8 with a 4.5" backspace and a 225/50/17 on it (narrowest tire recommended for a 17x8") your tires would stick out further than the 275/35/18's I run on 18x9's on my Duster. Can they work? Yeah, if you run your ride height high enough they probably won't rub. But if you lower the car from stock at all they'll interfere with street driving. Technically a 215/50/17 would put the tire in the same spot as my 275's, but the widest rim recommended for that tire is a 17x7.5", and those Year One rallies only come in 17x8 or 17x9.
DionR
Well-Known Member
This is why I like offset rather than backspacing. Offset tells you where the tire is regardless of wheel width or backspacing.
An 8” wheel with 4.5” backspacing is a zero offset wheel.
A 9” wheel with 5” backspacing is also a zero offset wheel.
Based on that, assuming the tire can be fit to the wheel, the tire will be in the same spot outside of and additional width due to stretching the tire onto a wider wheel.
Add that a wider wheel is going to need a wider tire, making things even worse.
I really don’t think so. I mean, I rolled and pushed my fenders to get down to the ride height I’m at with a 9” wide rim. Sure I’m running 275’s on them but the rim clearance itself will be an issue.
A 9” wide rim on the front really takes about a 6” backspace, a 5” backspace isn’t going to cut it unless you’re really working those fenders over.
You can do anything you want with enough metal work! But yeah, the YearOne 17" rims do not have enough offset/backspace for a lowered A-body. Or really any A-body if you genuinely want to run wider tires, running 225's on a 17x8 is a waste of rim width.
This will be a bit of a departure from the thread because all of this will concern 18's and not 17's. The 17's just lose around .3" to .4" on the backspace because of the outer tie rod end so you basically can't run 17x9's without the fender work. Like you could probably run a 17x9" if you did everything you need to run an 18x10, but only with a 275 max.
So on my Duster I was able to run the 18x9's with a +35 offset and the DoctorDiff brakes which add about 5mm per side to the track with 275/35/18's without really doing much of anything to the fenders at first. That's like a 6.17" effective backspace for the standard 73+ disk track width. But at the time my ground to the top of the wheel opening measurement was over 25" in the front. When I lowered the front more, so my ground to wheel opening measurement was sub-25" I started to get rubbing when I cross-axled over driveway approaches and things on the street. So at that point I rolled the fender lips.
I've since used the fender roller I have to "push" the fender out a bit more, and I have some extra room now to work with. I don't think 275/35/18's on 18x10's with my current set up would be a problem at all. The only place I ever rub with the current ride height is the inside top of the inner fender well, when the suspension is fully bottomed it just kisses the inner fender enough that I can see it in the undercoating. So I'm as low as I can go unless I reduce my suspension travel or modify the inner fenders, and that height issue also means if I went to 285/35/18's I'd have to deal with the inner fender since they'd be taller. But for the width I think I'm close, it might take a little more "push" on the front fenders.
Member Tomswheels ran 18x10's with 285/35/18's on the front of his Valiant. And from what he's posted anyway he did that with Hotchkis UCA's too, not SPC's. I know he used a port-a-power to push his front fenders, but the rest of the work he did was the fairly common corner trims and roll that I've already done on mine. He did a lot more work in the back to the rear quarters. If you look at his fenders and quarters you can see the flare/push in the front and especially the rear.
It's hard to capture in pictures, but you can see in this picture that the fender on my car is pretty pushed out and rounded in the middle. Honestly it might already be further out than Tom's Valiant. It still has a clear body line, but when you look down the side of the car there's definitely some flare to it. The thing is that Tom was running stock LCA's, so I'm pretty sure his suspension travel was more limited than mine is, I don't recall him talking about the top of the inner fender being an issue with full compression even with the taller 285's. But you can also see I have some room to work with to the fender lip, although the wheels being straight ahead is a bit deceiving for the turning clearance.
So for 18x10's, at least if you're looking at 275's or 285's, you'd need a fender roll and some "push", and the corner and fender brace work I did on my car as well. I extended the lower brace out about 2" and trimmed the corner back
The height issue comes in with shorter bump stops on the lowered cars, or in my case the shorter bump stops and the early version of the QA1 tubular LCA's that didn't have the bump stop built into the arm. Their profile adds about 1" of travel into the suspension, which I used to lower the car. So I maintain a little more than 5" of travel, pretty similar to the factory cars with factory bump stops and LCA's, just at a lower height (about 1 7/8" lower, a-b is 0 on my car).
So this modification that 72BBSwinger did is probably my next big bodywork mod for larger tires...
As for the frame rails I don't think they're an issue at all as long as your keep your backspace around 6.2", 6.3" or so. More backspace than that would probably cause issues between the lip of the rim and the UCA anyway, I know even my 18x9's hit a factory UCA at full steering lock suspension extension. The SPC's have a tighter "V" shape and clear. Because I have the QA1 tubular LCA's there's no steering stops, but my steering angle with my current set up is the same or possibly better before the tires touch the rails. I think 72BBSwinger had a 6.4" backspace up front at one point and apparently wasn't rubbing the frame on his car, but the lower ball joint steering stops have A LOT of variation. I'd say that's about the max backspace you can run, so, anything beyond an 18x10 will have to be accomplished with fender modifications.
And the ride height is a HUGE factor. Like the car in the beginning of this thread with the Year One wheels on it. If you run high enough you can run anything, but that really doesn't serve the function of better handling.
DionR
Well-Known Member
Here's another example of stretching the boundaries of what fits.
www.forabodiesonly.com
And this one:
Just for reference.
18x9.5 +12
Hey guys, My new wheels just arrived. 18x9.5 with a +12 offset, which equals about a 5.75” back space. I had been looking for some in this exact size and these popped up, brand new never mounted on anything, they’re MST wheels... the same eBay brand I’ve had on a few other cars. They have always...
www.forabodiesonly.com
And this one:
Just for reference.
michiganpat
Well-Known Member
to keep things simple, what works on a 14 or 15" wheel as far as offset will work the same on a 17. if you're running stock chrylser 15x7's with 4.25" backspace (1/4"+ offset), then the same size rim with a tire the same overall width and height should work (i.e. if there is a 215/60R15 on the front now on that 15x7 with 4.25" offset, that is 8.5" wide and 25.2" tall, then a 215/50R17 (8.5" wide, 25.5" tall) should fit on a 17x7 with 4.25" offset....on the front, you'll likely need to keep the outer face of the wheel/tire in the same spot to not have fender clearance issues, so if you want to go to an 8" rim, you'd likely need to go from the standard +1/4" offset to +30-32mm (basically all of the extra rim width is pushed to the inside), which is approx. 5.75" backspace. rear is really going to depend on your axle. met a guy with a '73 dart sport and a stock 8.25" rear. to get the tires centered in the wheelwell, he needed custom 15x7's with 3" backspace (so that would be the same as -1" offset)....for me, these wheels kind of speak to me....
Vision Wheel 148-7865SGMF19 Vision American Muscle 148 Shift Satin Gray Machined Wheels | Summit Racing
Yup, for sure!
Craig's fenders have the corners completely cut back because of rust, which I think not only effects the location of the corners but also how much rigidity there is in the rest of the fender lip. And he pushed the fenders out with turnbuckles as well.
Thing is, although he has the QA1 LCA's he has the later version with the bump stop that eliminates the additional suspension travel gained from the older style without the bump stops. If you look at his pictures when he had his car sitting on the bump stops, and think about that wheel being an inch higher, you can see how much it would decrease the clearance.
I think the same goes for the "price buster duster". He's running stock LCA's, so, even if he's running with shortened bump stops there's less suspension travel there.
Ultimately I think they both show that you can get a lot of tire under there if you're willing to roll/push/modify the bodywork. If you wanted to put an import style fender flare on there you could probably run 335's if you wanted to. But they also show how much ride height and suspension travel change the clearance you need.
Lol. Uh, yeah, if you want to run 17's with the same height and width tire as a 14" or 15" wheel/tire then you can use the same backspace, that should be REALLY obvious.
What is not obvious is that you can't use a 5.75" backspace on a 17x8 in the front or the back on an A-body. In the front with a 17x8" you can go up to about 5.6" of backspace with most rims, because the outer tie rod will interfere with the rim after that. So, no 5.75" backspace on the majority of 17" rims up front. But you can still run a 255/45/17 on the front with a 17x8 and a 5.6" backspace, which is much wider than anything you can pull off with a 15" rim. And of course in the back, regardless of which factory rear axle you have, you can't run 5.75" of backspace as it will put you into the springs.
There's also no reason you have to run a 15x7" with a 3" backspace, even with an 8.25" rear (which are narrower than the 8 3/4's). A 15x7 with a 4.25" backspace works just fine with most tires that will fit back there, 4" might be better with a 255. A 3" backspace would actually be limiting the width of the tire you could run. He likely just wanted his tires out closer to the quarters to look like they filled the wheel wells, because that 3" backspace doesn't actually center the wheel in the tub, it puts it closer to the quarters. My '74 originally had a 7.25" rear axle in it, same exact width as an 8.25". I was able to fit a 17x9 with 4.75" of backspace and a set of 275/40/17's on it in the back when it still had the factory spring locations and quarter lips. To be truly centered I think it would have needed to be about 4.5" of backspace, but that's still only a -12 offset, not the -25 those 3" backspace 15x7's had.
DionR
Well-Known Member
Funny.
Very recently, I was in the position to buy a pretty solid '73 Duster and was online looking at all A-bodies trying to nail down a value. Part of the impetus was the idea that maybe I would be better served to do my G3/T56 swap into something else and leave my current Duster "stock". So part of looking at A-Body values online was also looking at what I might want to buy if I did pivot. In the end, everything I looked at that wasn't a Duster just didn't hit the spot for me and I realized that if I did pivot, I wanted to stick with a Duster.
I didn't think about maximum tire sizes or anything, only that I just preferred the body style. But I like that it is one of the advantages.
In the back of the car that's actually not true. Barracuda's have the same inner and outer wheel tubs as Dusters/Demons/Dart Sports, or in other words 1" more than the hardtop Darts/Scamps/non-sport body cars. Like for like as far as stock/mods go Barracudas will take the same size rear tires as a Duster/Demon/Dart Sports
The problem is only the front fender, the front lower corner is more restrictive than any other A-body. But that mostly affects tire height up front, for width they're as good or even better than the other A's. And a small modification to the lower front corner is easy enough and solve the height issue.
michiganpat
Well-Known Member
gorgeous car. I need to get under my car and start taking measurements this weekend. I'm going to be doing a front suspension rebuild and drum to disk conversion on the front over the winter using A body disc spindles, for the rear I'm probably going with an XJ rear or YJ/TJ rear since those are what are easily available around me. I know on pre-73 cars the wheel mounting face gets pushed out further with discs, is it the same way going from the '73-up front drums to the stock disks? I thought the change to the drums in '73 pushed them out closer to the disc setup. my car currently has 205/70R14's on stock SBP rallyes and that's about the biggest diameter tire that will fit w/o catching the front corner of the fender with the stock rallye's bolt spacing. if I go 17's, my initial thoughts were a 235/45R17 in front, and 255/50R17 in back, likely Nitto NT555's....
First, my point had nothing to do with mini-tubbing. The stock wheel tubs on a Barracuda are the same as a Duster/Demon/Dart Sport. In fact, I believe that all '67-'76 A-bodies shared the same inner tubs, you can see my '71 Dart has the same indents as my '73 Duster and appear to be the same as the Barracuda (hard to say with the bracket in the way in the picture). The replacement inner tubs are all the same. The outer tubs are different, but shared by the Barracuda/Demon/Dart Sport/Duster. Those outers are 1” wider than the hardtop Darts/Scamps/valiants. So 275’s fit with no modifications, and 295’s will fit with a 1/2” spring offset and a little trimming on the quarter lip. A reverse tub like I did on my car can probably accommodate 315’s.
Here's a Barracuda, by @Bodyperson. It's already mini-tubbed here but the bracket is in the same spot on the tub (he narrowed the seat). You can kinda see the indents
This is my '71 Dart. Same indents, just no brackets since a hardtop Dart was never offered with a fold down seat.
Second, ‘73 up Dusters/Dart Sports with fold down seats have the same indent and similar bracket on the inner tub. Same exact issues as a Barracuda if you wanted to mini-tub. But it’s not like no one has mini-tubbed a fold down seat car, it has and can be done. And you can do it without cutting the seat down. You’d just remove the brackets, widen the tubs, and weld them back in.
Seat bracket on a factory fold down seat Duster
You can see in the picture above of the Duster bracket, and in the picture of the Barracuda above, that the seat bracket actually locates the seat pretty much even with the forward part of the wheel tub. The large 90° bracket extends around the corner of the tub and gets welded into the indent. But the part where the seat actually bolts to the mount is less than a 1/2" from the front of the tub. The upper latch bracket also wraps around the tub, but again, the actual latch is well forward of the front of the tub. So, if you got rid of the wrap around sections and cut back the pass through panel
You could basically just weld a flat plate with the threaded nuts attached to it in the same location as the original seat brackets. The bolts for the seat bracket would then extend into the wheel tub, so you'd have to seal them, but it's not like other bolts in the car don't already do this (seat belt mounting bolts, for example). You might even get away with a couple of large dimples in the wheel tub if you used a short bolt. The result would be that you don't have to section the rear seat at all, just deal with the small gap you'd get because the bottom of the fold down seat would move forward a smidge. On the later fold down Duster/Dart Sport cars it wouldn't require anything at all, there'd just be a slightly larger gap between the folded down seat and the pass through. The Barracuda might take a little more tweaking because I believe it does the pass through and fold down a little different.
But certainly people have done mini-tubs on Barracudas, and it's really no harder than doing one on a fold down seat Duster/Dart Sport. There is still some work to do on the interior panels, but that would apply to both the Barracuda and the Duster. Bottom line is I wouldn't avoid a Barracuda because of the fold down seat. And if you don't mini-tub the Barracuda is probably the best car for the widest tires possible.
I have yet to finish this Barracuda. My plan is not to narrow the barracuda seat but to weld-in a donor, dart, package tray and and back seat support. I'll use and narrow the non-folding dart seat. I plan to have a huge package tray that extends the length of the back glass. Maybe mount some subwoofers. I removed those brackets since this pic. I posted that pic to show how I left part of the floor attached to the tub. You can see where I drilled out the plug welds. Those holes got welded up. I cut the floor back so i could continuous weld the floor back together on top and TO the outer flange of the frame rail which I actually folded over to gain another half an inch. Kind of regretting it all now that I am about 15 years older and wish I could just drive the car again. Good old hindsight. Nice looking Demon @J.B.
That would definitely be one way to take care of it!
Although honestly, I did a bunch of research and even some fitting when I was doing the fold-down seat conversion on my Duster because I considered mini-tubbing it for awhile and was curious to see how much more difficult it would be with the fold down seat in place. Ultimately I decided not to do the mini-tub, but just because I didn't need more tire than the 295's I'd already decided would fit and I wanted to keep as much of the "pass through" space as I could because of all the stuff I end up hauling around in my Duster. Plus it gave me a good excuse to do the "reverse tub" and push the quarters out a big more to give the car more curves in the back.
But like my post kinda showed, I really don't think you'd need to do much of anything with the seat itself. A couple of flat plates with threaded holes or nuts on the back, in the stock locations, would work and you would basically keep the seat within about a 1/2" of its stock location, it would shift forward just a little bit. The bottom seat is plenty wide to give that up. Then you'd narrow the pass through around the tubs. The factory inner panels would just angle in, instead of being straight down, they could maintain their upper locations and would just taper in to meet the new inner tubs. That would probably give you a triangular gap to fill at the front of the interior panels, but I think that's just covered in carpet anyway so it wouldn't be super hard to deal with. Then you'd narrow the security panel to match the new inner panels, same deal it would just have to taper down.
Ultimately I think that would be easier to deal with than fabricating an entire package tray, but I could be wrong on that point. I'd worked out how I would do mine, although on the Duster the factory inner panels wouldn't work because they're just plastic. I was just planning to carpet the tubs on either side of the seat and make up a set of inner panels that would also get carpeted.
michiganpat
Well-Known Member
why I've always been hesitant to get too crazy with some of my mods/ideas over the years, it's nice just to drive them even if they aren't the fastest/best handling/best looking car out there. I'm confident I can get the suspension rebuild done over the winter (it NEEDS it with the play in the ball joints), but I'm resisting the "while it's apart" and go further. it really could use some attention to the rear quarters and such, but it's going to have to wait.
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