Tire Size help

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kdbunn

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I'm needing to choose a rear gear ratio for my '69 Barracuda and so was needing to pick a rear tire size. I'm looking for the widest tire I can fit comfortably. I will be going with a 17" wheel and I have a spring relocation kit on it. Rear discs on an 8 & 3/4. Don't like the rubber band look so I'm wanting some sidewall. I will determine back spacing later but was wondering if anybody has this setup or had any experience with this situation. Pics would be helpful. Thanks.
 
Relocation kit? Just the 1/2" inboard kit, or moved under the frame rails?
I've got 255-50x17s on the rear of my 55 chevy. 27"tall, 8 1/2" rim, 4.5 bs, definitely not a rubber band look. With the right wheel bs for your rearend width, should fit fairly easily. 275s MIGHT fit too.

One important question (I'm assuming I know the answer). Do you still have the 5 on 4 pattern?

Edit: nevermind, just saw a rear disc kit, so 5 on 4.5 for sure.
 
Thanks for responding. Relocation kit under the rail. And yes, 4.5 stud spacing. Would be nice to squeeze a 275 in there. Might have to find an old bald one and plce it in there. You wouldn't happen to have a pic of the tire on your '55 would you? I'd like to see the profile. If not, no worries.
 
I was able to fit a 325/50-15 on a 10"wheel into my lowered 68 Barracuda, with just the .5" offset kit.. Yes I had to pound the inner tubs a bit, to get enough clearance to the sidewalls, all in just one area, and I folded the lip up just a lil. I narrowed my rearend to run a standard 4.5" backspace. As I did that, I centered the housing between the tubs.
For straightline work, I get no rubbing. But around town, I can't act stupid in the turns.
I'm a streeter. Most of the time I'll be in Second gear, which is geared for 3500=41 mph ( Commando 4-speed.)
275s embarrassed me way too often by spinning me out with just a hair too much power; which at that time was around 330hp.
Currently, with about 400 or so hp, and with 295/50-15s on 10s; anything goes. I can go into a turn way too hot, and still come out with the tires on fire; so so much fun. But, as you can see, at 41=3500, I'm on the bottom of the power curve, in the heart of torque. So it's easy with a 750DP carb, to light them up. 325s should be on 11 inch wheels. If you install them on 11s and try to stuff them in the Barracuda tubs, it will not work.
295s on 10s is really a lil too small, but I have learned to run them at 24psi for long tread life, but they do tend to self steer around a lot of sweepers. I learned on the street, to like it. But the oversteer is noticeable enough to where, on a track you might find yourself in the weeds on a regular basis.
With 17s, you'll get more tread for the profile, but still have the oversteer at low tire pressures. So, Ima thinking a 275 on a 9/9.5 might be the way to go, but honestly, I'm guessing.
There is a guy on this Forum, I tried to tag him, but apparently I can't spell @blueAndBlue right cuz it don't work, lol. He'll find you soon enough.
EDIT, see next post. I wasn't even close, lol
 
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Thanks for responding. Relocation kit under the rail. And yes, 4.5 stud spacing. Would be nice to squeeze a 275 in there. Might have to find an old bald one and plce it in there. You wouldn't happen to have a pic of the tire on your '55 would you? I'd like to see the profile. If not, no worries.
I had a shot that would show that exactly..... but I think it was on my tablet that died.
I'll get you a shot in the morning.
 
substantial sidewalls on a 17 inch wheel - that's going to be one tall tire!
 
Barracuda’s can run 275’s with the springs in the stock locations, no relocation or offset needed.

The factory wheel wells will fit a 295.

With a 3” relocation and a mini-tub you could put 345’s in there if you wanted. But if you just did the 3” relocation and have the stock wheel tubs then a 295 is the biggest you can go. Even with just a 1/2” spring offset kit the tubs become the limiting factor. Anything up to around 28” tall will fit without too many issues.

With 17’s a 275/40/17 will work on a 17x9”, so a 275/50/17 would work on that as well if you wanted, although a 9.5” would be better.

I run 295/40/18’s on 18x10’s on my Duster with just a 1/2” offset and a little quarter lip trimming. The factory tubs are the same for Barracuda’s and Dusters.
 
255-50x17 nitto 555 g2's Closer to 26" tall. You could look for a 275-50x17 (nitto makes those too, 555 G2)

IMG_20250111_164514.jpg


IMG_20250111_164454.jpg
 
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255/50R17's are 27" tall and 10" wide. 275/50R17 are almost 11" wide and 28" tall....I'd look at either for the back. front you'll probably need to do something more like a 245/45R17 to fit....
 
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