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15 x 15 wheels

DMR440

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Hey guys I have a 68 Coronet 500 and I'm thinking about tubbing the car to fit 15 x 15 wheels. I'd really like to run Centerline Auto Drags. My question is, if I were to tub the wheel housings to the frame rails, the wheels will fit no problem, how much do I shorten the diff by? Or what would the overall length from backing plate to backing plate be?

Armed with this info It would be cheaper and easier to buy something already set up, ideally something second hand. I'm currently running an 8/34 with posi and 355 gears. Depending on whats around and budget, I may just use a rear spring relocation kit over a 4 link. Right now I'm just doing some research at the moment.

I'm running a 440/auto for power and this will be used as a weekend warrior, I'd like to go the pro-street / old school pro-stock look but will most likely retain the stock type front suspension.

I'm not too keen on the idea of a ladder bar rear setup for the street as I hear from various friends/owners with this setup that the car doesn't like to turn corners too well. Perhaps relocated springs, shortened diff and a frame mounted rear sway bar might do the trick?

Keen to hear any feedback. :icon_pray:
 
Unless someone has done the exact same modifications as you or, conversely, has done mods that you want to duplicate, I think the only way to get an accurate measure is to mock it up and roll around on the floor with a tape measure, a plumb-bob, and a calculator.

That kind of surgery and fabrication takes some dedication. It sounds like a cool project, though. Start a build thread and show what you did and how it turned out. I'm not 100% sure, but I don't think the typical off-the-shelf spring relocation kit is gonna get you to where you wanna be. Tucking 15x15s is gonna take some doin'.
 
I concur with what he said. Also, you never mentioned anything about what size tires you want to run. Tires are what you are really tucking in and more than likely the tires required for a 15in wide rim are gonna have a section width of 18-20 inches and a diameter of around 30 inches. If you have that much space from the frame rail to the fender lip with a couple inches to spare then great. If you don't have that much room, get ready to start doing some serious cutting.
 
I know its none of my bussiness ,but i dont understand why people tub cars,unless there is a rust issue or a track car,maybe someone could explain it to me .
 
I know its none of my bussiness ,but i dont understand why people tub cars,unless there is a rust issue or a track car,maybe someone could explain it to me .

I would have thought that the usual reason for tubbing is to fit tires larger than the factory wheel house would allow.
 
Because "tubbing" a car is a way better idea than say, jacking it up and putting on 30in rims with low profile tires. If that look hasn't made its way up to Canada yet, consider yourself lucky.
 
I hear ya Rocky,that crap is here to,But once you tub it ,can it be returned to factory.I have a pretty good size tire on my Belvedere without tubbing.Sorry not trying to high Jack this thread
 
The inner wheel tub really tapers in {even the body narrows some at the top}, up at the top on the outside of the inner wheel tubs is a few inches narrower, creating rubbing issues as the tire grows or body lean or flexes, when it goes higher into the wheel well... IMHFO that's the biggest part of the problem putting larger tan a 29.5"-30"tall x 12.5"wide tire {actually near 14" wide at the girth/bulge} with the outer wheel well lip rolled under, so it could clear with out cutting the slicks/tires, it had a set of MP S/S springs & relocated inward, that had allot more arch & ride height too {than stock}, latter went to CalTracs & Mono Leafs it was extremely tight and 1" lower, with nowhere near a 15" wide tire, on these 68-70 B-Bodies anyway... I never ever could fit a 15" wide wheel or tire in any of my cars, with out any rubbing on the both the frame & outer wheel wells, remember the tire flexes side to side & grows in diameter & suspension goes up & down too... IMHFO usually a 15"x12" wide rim was more than plenty, with MP spring relocation kit's to have adequate tire clearance for body lean/body torque, tire growth & flex side to side, with out actually having to move the frame rails inward &/or Narrowing the housing, but the outer side of the tub @ a minimum, needs to be modified, or replace the tubs all-together... Good luck & have fun... Build it how you want it, anything can be fixed or changed back to stock, with $$$ & the proper knowledge &/or tools...
 
In my novice opinion, i think you'll find with a mini tub and stock rear frame rails you can fit maybe a 13.5" wide tire max - if your back spacing is dead nuts on. I have 295x65xR15 ET Streets (about 30" x 12.5") on my 69 belvedere with a mini tub and stock frame rails and I have maybe 1" clearance on the outside and 2" on the inside. With rear squat and balooning of the tire under acceleration and at speed, I'm not sure there is room for more than 13" or 13.5". Now keep in mind that this is a plymouth b body, and if i recall (budnicks knows this for sure) i believe the dodge b bodys have a bit less wheelhouse.

Reason I mention this is this - for 15" tires you probably need to relocate frame rails but if you can deal with 1.5" less tire, all ya gotta do is spring relocate and mini tub.

Here's some pix of mine when it had 12.5x29 sportsmans:
image.jpgimage.jpgimage.jpgimage.jpg

image.jpg image.jpg image.jpg image.jpg
 
The inner wheel tub really tapers in {even the body narrows some at the top}, up at the top on the outside of the inner wheel tubs is a few inches narrower, creating rubbing issues as the tire grows or body lean or flexes, when it goes higher into the wheel well... IMHFO that's the biggest part of the problem putting larger tan a 29.5"-30"tall x 12.5"wide tire {actually near 14" wide at the girth/bulge} with the outer wheel well lip rolled under, so it could clear with out cutting the slicks/tires, it had a set of MP S/S springs & relocated inward, that had allot more arch & ride height too {than stock}, latter went to CalTracs & Mono Leafs it was extremely tight and 1" lower, with nowhere near a 15" wide tire, on these 68-70 B-Bodies anyway... I never ever could fit a 15" wide wheel or tire in any of my cars, with out any rubbing on the both the frame & outer wheel wells, remember the tire flexes side to side & grows in diameter & suspension goes up & down too... IMHFO usually a 15"x12" wide rim was more than plenty, with MP spring relocation kit's to have adequate tire clearance for body lean/body torque, tire growth & flex side to side, with out actually having to move the frame rails inward &/or Narrowing the housing, but the outer side of the tub @ a minimum, needs to be modified, or replace the tubs all-together... Good luck & have fun... Build it how you want it, anything can be fixed or changed back to stock, with $$$ & the proper knowledge &/or tools...

Awesome this is the kind of feedback I was looking for. I had a 72 Challenger drag car that had 15 x 15 welds on the back with a 16" wide tyre (as stated on the side wall). They were Mickey T's. Looking through the photos, I do remember that the inner wheel housing was missing the inner skin so to speak, most likely for reasons you have mention in the above post.

Ok so I guess I should give a little more detail as far as the Coronet goes. It originally came out with the 318, now has the 440 etc. Rust is an issue, the frame rails are shot and will need to be replaced along with the rear cross member, spring hangers and torison bar cross memeber too. They are coroding/rusting from the inside out. I need to replace the front floor pan as well as the trunk pan. The inner wheel housings have a couple of small rust holes showing too. This is all I can see so far without sandblasting the black under sealant to really get a good look at it all.

So I'm thinking since I have to go this far and the cost of parts from AMD I may as well build it the way I really want it. Custom rolled tubs and from what I have just learned from your post I may as well move the frame rails inward while I'm at it while replacing them with new ones. So I'm probably best off getting the wheels and tyres first and going from there. Tyre height would be around 30" to 34" and I'd be looking at dropping the car down so the outer wheel lip arch sits just above the center of the wheel the way the pro stocks did. Making the front tyres fit and turn will be fun too figure out too. Do you think I might be able to get away with Caltracs etc with lowering blocks?

Has anyone had a hand in build a pro stock A B or E body? Some drag racing with the car is a given, but will mostly be driven on the street with family, so retaining the stock back seat/interior is a must with acception to Charger or Cuda buckets.

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In my novice opinion, i think you'll find with a mini tub and stock rear frame rails you can fit maybe a 13.5" wide tire max - if your back spacing is dead nuts on. I have 295x65xR15 ET Streets (about 30" x 12.5") on my 69 belvedere with a mini tub and stock frame rails and I have maybe 1" clearance on the outside and 2" on the inside. With rear squat and balooning of the tire under acceleration and at speed, I'm not sure there is room for more than 13" or 13.5". Now keep in mind that this is a plymouth b body, and if i recall (budnicks knows this for sure) i believe the dodge b bodys have a bit less wheelhouse.

Reason I mention this is this - for 15" tires you probably need to relocate frame rails but if you can deal with 1.5" less tire, all ya gotta do is spring relocate and mini tub.

Here's some pix of mine when it had 12.5x29 sportsmans:
View attachment 135410View attachment 135409View attachment 135408View attachment 135407

Hey HT413 thanks for the post, and cool car man! I have a 9 inch wheel on the car now with 275/60/15's. I'm sure with a lower profile I could get away with 295/50/15s. I could consider living with a 13.5" tyre and set it up the way you have, that will depend on my budget or most probably patience lol. How much more of an effort would it take to get your car sitting a little lower the way the pro stocks used to? Assuming you wanted that look of course :headbang:

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And wow you did a nice job on the tubs too! Looks as though your retaining the stock back seat too? How wide is the actual wheel?
 
. Do you think I might be able to get away with Caltracs etc with lowering blocks? Has anyone had a hand in build a pro stock A B or E body? Some drag racing with the car is a given, but will mostly be driven on the street with family, so retaining the stock back seat/interior is a must with acception to Charger or Cuda buckets.

I have had experience in building a few Pro Stock & Pro Mod experience along with Fuel/Alky & Blown Gas/Altered's, even also driving quite a few too also, among other Drag Racing classes, but not in a any 60-70's B-Body, but I've been 8.58et @ 156mph in a 68 RR 3520#'s on N20... My experiences in those classes was in 80's & 90's mostly match racing & smaller lessor known tracks, but very limited up-to 2007, just west coast match races really, mostly GM Corp./Pontiac Trans Am & a Camaro, Altered was FI &/or Blown Wedge &/or Hemi Powered... but these B-Bodies in Pro Stock was 40+ years ago, the tire technology & suspension options etc. was completely different, than what we have available today, kind of apples & oranges in comparison... If your going to do all that work, I suggest you put a 4 link or ladder bars & coil-overs...

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I would call Calvert CalTracs & talk to them, I don't think the lowering block are a good idea with CalTracs, I could be wrong...

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Has anyone had a hand in build a pro stock A B or E body? Some drag racing with the car is a given, but will mostly be driven on the street with family, so retaining the stock back seat/interior is a must with acception to Charger or Cuda buckets.
.
 
And wow you did a nice job on the tubs too! Looks as though your retaining the stock back seat too? How wide is the actual wheel?

Thanks, but i bought the car like that... it was exactly how i wanted it - mini tubbed but retaining the back seat (i spend way more time taking the kids for ice cream than racing lol).

I'm running a 10.5" wide rim, not exactly sure the back spacing. i would love the car an inch or so lower, but biggest problem I have with lowering the car any further is I'll never get the tires off. I'm running QA1 coil overs with a 4 link and track bar and I have to wrestle the tires off as it is lol. Pretty sure the track bar is what's limiting my travel - I was thinking about installing a removable linkage like they have on sway bars on serious offroaders but I haven't really pursued it. Food for thought for you though.
 
I highly doubt a tire that big will fit & still maintain the whole back seat
 
If you're replacing the rear x-member/shock mount anyway, make it ultra stout and use ShockWaves from AirRideTechnologies. These mount in place of your regular shocks. The leaf springs then act as axle-locators only cuz you're riding on air. You'll get height adjustability for when you've got the family and all the family-stuff loaded up. Seems like a win-win, the only problem I can forsee is the bulk of the air bags themselves....you'd have to maintain enough axle width to physically fit them in there.
Usually guys demonize air shocks because A) that original shock mount is not designed to hold up the weight of the car (true) and B) thier's was all crappy and rusty and that's why it tore the *** outta thier car ending thier air-shocks experience badly (also true).
 
cool thanks for all feedback so far. I guess thinking about it more having a 15" tyre is my goal and not the actual wheel itself. Thanks for helping me clear that much up at least. A 4 link would really be the way to go by the sound of it, I will have to see what's around when the time comes. I have looked at kits on racing junk etc as well as the Alterkation kit and stuff like that. I'm still in two minds about leaving the frame rail location where it is and just moving the springs and working the tubs from there, keeping the stock 83/4 width, for me budget has a lot to answer for if ya know what I mean. So 13.5 tyre would most likely be max with this route?

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Here's the look I'm going for. I don't like the tilt deck lid but that's just me. Nice car though
 
If you're replacing the rear x-member/shock mount anyway, make it ultra stout and use ShockWaves from AirRideTechnologies. These mount in place of your regular shocks. The leaf springs then act as axle-locators only cuz you're riding on air. You'll get height adjustability for when you've got the family and all the family-stuff loaded up. Seems like a win-win, the only problem I can forsee is the bulk of the air bags themselves....you'd have to maintain enough axle width to physically fit them in there.
Usually guys demonize air shocks because A) that original shock mount is not designed to hold up the weight of the car (true) and B) thier's was all crappy and rusty and that's why it tore the *** outta thier car ending thier air-shocks experience badly (also true).

Or Ride-tech bolt-in 4 link & either coil-overs or airbag shocks
 

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The 13.5" is just an estimate from my own car. You'd have to obviously measure / mock it up on yours. I know u know this, just sayin.
 
All good I might go and pull a wheel off shortly and have another quick measure up. Plenty food for thought though, thanks again for all feedback and comments. I love this forum! :icon_thumleft:
 
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Hey I think I can help. I have a 68 Coronet I am building and I did the mopar spring inboard kit, 440/Hemi leaf springs, 3.5" mini tub to the frame rails, and stock axle width. 8-3/4" 3.91 Posi. The inside fender to frame rail is 16". I plan to run M/H radial PN:ROD-07 on a 15x12 widened steel cop wheel. When choosing a wheel width first look at the tires section width then the suggested wheel width. I don't think you will fit a 15"x15" with a mini tub like mine. The wheel well narrows toward the top. Let me know if you have questions or want some more pics.

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These are the tires I think I can fit in my car: M&H#676-ROD-07R M&H Drag Radial Tire 390/45R15, 672-6642
Sportsman S/R Radial 29'' x 15''R x 15''LT,522-19200PS Pro Street RadialTire Size: 29x15.50R-15LT

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