Rear tire fitment

[Riggins44]

I am sure this has come up before but I could not find an answer here on the forum. I recently purchased new wheels and tires for my 68 Dart. 15 inch wheels and I installed 255/60/15's on the rear but it is a tight fit. There is only about 1/2 inch space between the rear tire and the leaf spring. Is this enough? I can't see how the leaf spring could shift sideways but maybe the sidewall could bulge out under hard cornering but I do not know. Just wondering if anyone experienced any issues with this set up? The tire to quarter lip space appears to be okay as it is an inch or so. Thank you for any helpful input.

 

[pntastar69]

If you have a sway bar, it should be ok. I have a finger width to the wheel lip with no rubbing. I added a sway bar in the front and made a huge difference cornering.

 

[mopowers]

You should be okay with 1/2". Have you taken it out for a spin yet? If you needed to and your wheel studs are long enough, you could put in a 1/8" or 1/4" spacer to buy a tad more since it sounds like you've got plenty of space on the outside.

 

[Dana67Dart]

Is the rear particularly high in the air?

I have 215 70R14 and I have about 1/2 inch to the spring (maybe 3/4) and some clearance to the lip. But I don't see how with my stock rear springs I could add another 1.5" (40mm) (3/4" on each side) to the tire width on my 67 dart.

If the rear is high you might want to load up the car with yourself and 3 of your larger friends and see where it sits.

 

[pntastar69]

What is the wheel backspacing?

 

[33IMP]

1/2" to the spring, you're fine. I've run tighter than that for years.
If you had 1/2" to the fender, THAT I would worry about.
Now, crawl under the car and see how close you are to the inner wheel tub. Often closer to the tire than the spring
IF you have long enough studs, you could add a small spacer.... but NOT the universal fit cast garbage!

If you are still 5 on 4, you'll need to use a 5 on 100mm spacer. Not perfect, but close enough for a spacer. NOT close enough to use a 5x100 wheel, however.

 

[toolmanmike]

Nothing more to say that already has been said. My Swinger is close but no rubbing. One side I can't slide my fingers through between the tire and quarter lip but it doesn't rub.

 

[RustyRatRod]

Drive it around give it hell and find out.

 

[Riggins44]

What is the wheel backspacing?

It is 4.5" currently.

 

[Riggins44]

1/2" to the spring, you're fine. I've run tighter than that for years.
If you had 1/2" to the fender, THAT I would worry about.
Now, crawl under the car and see how close you are to the inner wheel tub. Often closer to the tire than the spring
IF you have long enough studs, you could add a small spacer.... but NOT the universal fit cast garbage!

If you are still 5 on 4, you'll need to use a 5 on 100mm spacer. Not perfect, but close enough for a spacer. NOT close enough to use a 5x100 wheel, however.

Okay. Thank you. It is just under 1/2" between tire and leaf spring. I do not want to use a spacer. It is the sbb 5x4 axle.

 

[GoneShawn]

I would admit I not with the ability to advise, but I did read just a bit on some of that movement recently and found this interesting although, Im not a source of knowlage or fact on the matter. ​

I never realized the leaf spring actually steer ...lol​

(just something Ive read;)

​

Leaf Springs and Cornering Performance​

Tracking Behavior​

Leaf springs can exhibit lateral movement during hard cornering. This is due to their design, which allows some flex and steer. The amount of lateral movement can vary based on several factors, including the type of bushings used and the overall setup of the suspension.

Factors Affecting Tracking​

• Bushing Type: Rubber bushings can create more lateral movement compared to solid or spherical bushings. Upgrading to stiffer bushings can help reduce unwanted movement.
• Shackle Design: The design and placement of the rear shackle can influence how the leaf springs behave under load. Sliding shackles may provide better performance by allowing more freedom of movement.
• Panhard Bar: Adding a Panhard bar can significantly improve tracking by limiting lateral movement. This is especially beneficial in high-speed cornering situations.

Recommendations for Improved Handling​

• Upgrade Bushings: Consider using solid or spherical bushings to minimize flex.
• Install a Panhard Bar: This addition can help stabilize the rear end during cornering.
• Adjust Spring Setup: Modifying the leaf spring pack or using sliders can enhance handling characteristics.

By addressing these factors, you can improve the tracking and overall performance of leaf spring-equipped vehicles during hard cornering.

Does driving habbits play a roll? I cant imagine it moving more that 1/2" if the set up is tight? do you drive like Mario Andretti? lol

 

[Dana67Dart]

Does driving habbits play a roll? I cant imagine it moving more that 1/2" if the set up is tight? do you drive like Mario Andretti

Just my thoughts.

When one leaf compressed the distance from the front mount to the center of the perch gets longer, ( flattening a curve in the spring)

And

On the other end unloading the spring on the other side does the reverse.

The combination would result in a slight turning of the rear axle. Enough to be noticable ??????

 

[matthon]

Enough to be noticable ?

No, but at least it's turning the same direction as the front.

 

[matthon]

67 Barracuda, had 15x7 4.5bs with 255/60s, sbp rear.
Passenger side was close to the spring but did not rub.

Installed a rear swaybar and on hard cornering the car would stay level but the tire would rub the spring on the passenger side only.

Went with bbp axles, 15x8 4.5bs 275/60s no rubbing whatsoever.