Mt 325-50-15

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slowdown

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So I'm finally ready to get a different width of tire an rim. I am running 275-60-15 by Goodrich on 15x8 with 4.5 back space. i've done some measuring today an have a total of 14 1/2 inches from the inside well to the inside fender lip. And from the tire mounting surface on the drum I have 6 1/4 inches to the inside fender lip. It looks like if I can run a 12 inch rim with 7 inch back space I should come out with about a 1/2 inch of clearance on both sides of the tire. This is on a 68 dart with a mini tub an spring relocation. I skimmed through the 325-50-15 forums an only found one dart but had the rear narrowed to get the deeper look. Are there any others here with this tire under a dart? And did u run into other problems getting them to fit? I think I can put these tires on a 12 inch rim. Its been hard to pony up for new rims an tires when I already have the ones I have but the tires will just spin when I get on it an I intend to take it to bandimere this summer. Fingers crossed.
Oh the rims I already have are weld draglite, an the wider one I intend to get are going to be weld Draglites. there where a lot of dusters with this sized tires that I found, but I just didn't find many darts. Thanks again.
 
its gonna be hard to fit that wide of a tire without some major surgery. the best thing I can tell you is to remove tires you have and place the new tire in there place without the rims installed.(obviously with the car on jackstands at ride height) then you can get an I dea where the mounting face will land in relationship to the tire ttreadpattern. make marks on the floor with a crayon for the tread pattern and use a line with a sinker on it for the dimension where the axle mounting face will land in relationship to the floor. this will give you some kind of idea what off set you will need for the rims.
 
I have a 69 Dart that a previous owner cut the quarters for a hemi clone look and also relocated the springs and installed full tubs. The car came with 325-50-15 sport comps on 15x10 wheels with 7" backspace, but also had 1/2" spacers. Over this winter I narrowed a housing to 46" overall and now have the same size tires on 15x10 cragers with 3.75" backspace. I have between 1/2" - 3/4" clearance to the springs and at least an inch to the quarter everywhere. I also put new super stock springs on so i really think I could have put a larger tire on if I had wanted but width wise this is perfect.
 

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I have much the same set up and was wondering if I could fit the 325/50/15's on my dart. I have 15 x 10 Convo Pro's with 30 x 11.5 x 15 Goodyear slicks on them now. Would like to know the measurements on the 325/50/15 on 10" wheels, tread width and over-all width from sidewall to sidewall?
 
You will need 7 1/2" of backspacing to run a 15X10 wheel with a stock rear end width with a 325/50R15 tire.
 
Ordered them today. 15x12 with a 7 1/2 back space I transfered measurements to the floor with level an framing square. It looks like it should leave about a 1/2 inch to 5/8 on each side of the tire. Summit said they have no problem taking them back if they don't work as long as I don't mount them. I'll get the tires later after I am sure I measured right. Thanks
 
Same as what Brian T said. We just mini tubed a 69 Dart at my shop. The recommended rim size for the MT ET Street 325 50 15 is 15x10. The section with is 13.2". We're using a 7.5" backspace rim. We also have 1/4" hub centric spacers on hand and will mill them side specific for the tire to be centered exactly in the tub.
 
GMachineDartGT said:
Same as what Brian T said. We just mini tubed a 69 Dart at my shop. The recommended rim size for the MT ET Street 325 50 15 is 15x10. The section with is 13.2". We're using a 7.5" backspace rim. We also have 1/4" hub centric spacers on hand and will mill them side specific for the tire to be centered exactly in the tub.
Click to expand...
Thought he was talking to Ronw about 10 inch rims. I thought advertized was up to 12 inch rims. I did'nt know 10 inch rims where recommended. Thanks.
 
Slowdown, I forgot to say that my rear(8 3/4 ) is narrowed and don't require the back spacing as stated. So, is the 13.2 the sidewall to sidewall measurement? And is the 10" wheel acceptable for this tire? How much tire pressure is used?
 
Wow they showed up today, looks like measurements are good, holy cow I know there only 12 inch rims but these things look huge. I had a friend loan me a 13 inch tire to slip up in the fender well where I can get a good look at where things are going to sit. I've looked at the tape measure an 13 inch tires don't seem that wide till u got one in your hands. Now it's time to order the tires.
 
I'm running those tires but on 10" wheels. I know I probably could go 11" wheels on it. 12" I'm not sure. It will probably would work but it's going to be tight as long as the spacing is dead nutz on.
 
The section width on my BFG 325/50-15 Drag radials is 13.6 on a 10" wheel at 24psi.
On a 12 inch rim at race psi, the section width could easily be an inch or more wider. My tires are wearing very well on 10s.

If you do the math: 325section width on a 70%rim, it works out to 12.8 inch section on a 9 inch rim.
That would be the tire manufacturers criterion.
As to my 13.6 section, Ima guessing the 10 inch rim adds .8 inch to the section width.So on a 10 inch wheel, the 325 becomes a 345.
Therefore Ima guessing the 12 inch wheel could add even more section width.Perhaps as much as 14.8(a guess), or more.
 
I measured a mt sportsman pro with a sec with of 13.1 on a 12 inch rim with the tire on the floor an a strait edge it measured 13 an about an 1/8. I guess that's why I thought I could get away with 12 inch rims. The tires are still in transit maybe Monday I should get them, I'm going to check it out carefully before I mount them. I'm hoping they fit but if not I can send the rims back for another size if it's to close. I put the rims on the car, held on with a couple of lugs not tightened down just by hand. And with a strait edge on the face of the rim with the strait edge all the way up to the fender there's a good 5/8 space. And about the same on the back side of the rim. Got my fingers crossed.
Explanation on the sportsman tire, was a local guy was selling them, they where new tires but the draglite rims new days where long gone, I didn't buy them. They where on a 12 inch rim though. He wouldn't split them from the rims nor lower the price. Im hoping the drag radials sidewall flattens out as the rim gets wider, I'm hoping anyway. But I guess I'm going to find out. Thanks..
 
They fit. About 5/8 space front an back. Rubs a little in a tight turn. when it rubs it's on the inside wheel well. I think I can massage it well enough to get it to stop. But all an all very happy. I played it conservative when I originally ordered tires an had all this space in the wheel well left over. An after all the work of mini tubbing it, I was a little disappointed I didn't go with a fatter tire. Not a issue anymore these things are fat.
 
Mounted on a 12 rim with 30lbs of air it's 13 3/4 section. I did call mt before I mounted them, they said a good rule of thumb is a 1/4 added to section width per inch of rim. The tires are advertised at 13.10 on a ten inch rim an he said to add a 1/4 to that for every inch wider I go with rim width. Any how it's pretty close to that. I'll add a couple of pics today to my gallery of them.
 
Ok; so a 325/50-15 M/T, has a 13.75 section width, on a 12 "rim, @ 30 psi.
Good to know. And thanks for posting.
BTW, that M/T, @ 13.75 section, is now about a 350/46-15. Jus playin the numbers game! lol
And when its aired down to race, it may become a little fatter yet, becoming something like 360/45-15.
Aint math fun!
 
BFG, G-Force DRs 325/50 x 15 on 12" wheel = 13 1/2" section width by 27 1/2" tall.

To get that size rating, the manufacturer specifies a rim of 70% of the section. So .70 x 325 = 228 or 8.98inches, which gets rounded to a 9incher. On that 9" rim the section will be close to 325mm. If you work the math backwards the section width will be 9/.7 x 25.4= 326.6mm,which is rounded to the nearest 5mm; 325. Now the aspect ratio, being sidewall height to section width will be 326.6/ (27.5-15)/2 =48.6%, which is rounded to 50%. Thats what makes a 326.6/48.6-15 into a 325/50-15

Well lets do the math on that G-force,mounted to a 12 inch rim..
The section width is now a measured, 13.5 or 342.9,which would be rounded to 345
At 27.5 tall; 342.9/ (27.5 - 15)/2 =6.25 ; so the aspect ratio would be 6.25/13.5 =46.2%, which rounds to 45. So now,that exact same DR tire is a 345/45-15.
Sweet.
 
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