Rear Duster Tire Size

-
K

KOZ45

Well-Known Member
Joined
Mar 11, 2018
Messages
508
Reaction score
148
Location
Indiana
Duster came with G50-14 on 14x8s..........Those tires were dry rotted and the wheels were actually both bent

I found some 14 x 6 aluminum slots with 3-3/8" backspacing for my SBP rear 8-3/4" axle

I know the backspacing is not ideal for the car but it's what I am working with

With the wheel mounted on the car and two lugs installed to hold it secure, I did some measuring:

I have about 2-1/2" of room from the leaf springs to the back edge lip of the wheel

I have about 3-1/2" of room from the inner wheel well to the back edge lip of the wheel

I have about 1-3/4" of room to the outside of the rear fender to the outer/front edge lip of the wheel

I have about 1/2" of room from a lip on the rear fender to the outer/front edge lip of the wheel

Again, not an ideal wheel to run but its what I have found to match my front SBP aluminum slots

With all this being said, what size 14" rear tires can I run? Should I make sure the tire fits inside the rear fender wheel well opening?

Or, is it ok to run a wider tire that may stick out? I was concerned about body and tire damage with suspension movement

Here is how wide the rear tire was when I bought the car, with the G50-14 and the 14x8s with 3-1/2" backspacing

20200724_160134.png
 
It's less than not ideal. A 1/2" from the outer lip of the wheel to the inner edge of the quarter? You need at least that much to keep from rubbing if your tires are going to be inside the wheel wells. So if you're not counting on your ride height to keep the tire and quarter from ever occupying the same space the best you could do would be something with around a 7" tread width (same width as the wheel outside edge to outside edge). Even that may not work, depending on your ride height, because the section width will be more than 7". Even a 215/70/14 with a 6.6" tread width has an 8.7" section width, which would mean the widest part of the tire would hang out more than 3/4" past the outer lip of the rim, or a 1/4" into your bodywork if they're the at the same height.

So your next question "is it ok to run a wider tire that may stick out?" is what it comes down to. Is it? Only if your suspension is stiff enough, or the ride height is high enough that the body of the car and the tire can't ever be in the same place at the same time. So, either you need to have at good 3" (or more) from the tire to the quarter, or you run suspension stiff enough that it limits the upward travel of the wheel to less than the space you have between the body and the wheel. Lots of people run tires that won't fit inside the body of their car. Usually with SS springs, so 160 lb/in springs that also raise the ride height so there's at least a couple, if not a few inches between the body and the tire. Of course ride quality and handling are out the window at that point, but it's all about what you want.

If you want your tires to fit inside your wheel wells, even 215/70/14's might be a stretch depending on your suspension. It looks like you have some rake, but you also have some relatively short tires (sub 25"). Taller tires will also reduce your body clearance. If you don't mind the '70's "stink bug" look with the rear end of the car up in the air and the tires hanging out like a bro-dozer then you can run whatever you like. But if the suspension ever gives enough to allow the tire to hit the body you'll be in trouble.

If it were me, I'd be looking for some 15x7's with at least 4.25" or more backspacing. But that's just my opinion.
 
My car does/did have a rake when I bought it

Long adjustable rear leaf spring shackles and traction/slapper bars

20181030_194748_zpsmasf9yuc.jpg
 
KOZ45 said:
My car does/did have a rake when I bought it

Long adjustable rear leaf spring shackles and traction/slapper bars

View attachment 1715646872
Click to expand...

A smorgasbord of bad ‘70’s suspension ideas. The long shackles screw up the suspension geometry, not to mention introduce more flex and instability into the rear suspension. And slapper bars aren’t all that effective on mopar leafs if the suspension is set up properly.

A set of 002/003 SS springs would accomplish everything that stuff is supposed to be doing while maintaining better suspension geometry and hooking better.

But if you take that stuff off without replacing the springs your current tires probably won’t fit.

KOZ45 said:
The stock G50s (mounted) measured 24-5/8" tall
Click to expand...

That’s a little taller than the conversion chart I was looking at, but that’s still a short tire. Personally I like to keep the tires at least 25-1/2” tall, especially in the rear. 26”-27” looks better. But unless you move the wheels further inboard or run much narrower tires anything taller than what you’ve got will probably hit the body.

The long shackle thing was just a cheap hack to raise the car to run those wheels. What you do to fix it depends on what you want. If you want to keep the ‘70’s rake and tire look get a set of SS springs. They’ll maintain the ride height and allow the suspension to work much better, while allowing you to keep hanging the tires outside the quarter lip without interference as long as you don’t get too crazy.

Or, if you want to set the car down to a more original or even modern stance, I would buy rims with the proper backspace. If those shackles have been on the car a long time you might still need leaf springs though, as the ones on it now are probably hammered.
 
Be careful when running wide tires in the back, on skinny rims . In order to get the treads flat to the road, you might have to drop the pressures way down.
This throws the handling for a loop. When you turn, the weight of the car causes the tread to roll under the car, while simultaneously that outside tire will receive the weight of the tire, and the suspension will be allowing the weight to drop down. This also causes the body to side shift on those way-too-long shackles. So now you gotta go look at what is happening on the other side of the axle, the inboard side.
Rear springs for handling work best with short shackles and when running relatively flat under load.
IMO, bite the bullet and do it right the first time.


And no, you can't put those 8s on the front. Well you can, and with 245s it will look sorta good, but it will steer wonky and wander big time. On the front, the mounting flange more or less needs to stay in the center of the wheels. That means an 8 needs close to a 4.5bs. and neither a 14, nor a 15 with a 4.5bs and a 245, can be mounted without hitting a caliper or a ball-joint or in a turn; rubbing on the frame, the strutrod or the fender.

I think this guy, covered it pretty well.
72bluNblu said:
A smorgasbord of bad ‘70’s suspension ideas. The long shackles screw up the suspension geometry, not to mention introduce more flex and instability into the rear suspension.
Click to expand...
 
I goofed, the rear wheels I have are 14 x 7, not 14 x 6 as I initially posted

According to what I have found, I can run the following width on 14 x 7 wheels:

215
225
235
245
 
Just because you can install a 245 on a 7, doesn't mean that you should. With optimized air pressure, it will lay the same skinny blackies as a tire one or two sizes smaller. And if that optimized pressure is too low, it will handle poorly in the corners.
IMO, with a BB under the hood, you can't afford to fool around with skinny tires. You are just inviting trouble.
Wheel Vintiques will sell you a couple of custom backspace Rally wheels pretty darn cheap.

245s are not adequate.
I have a 367, in a 108wb, 68 Barracuda, which is pretty much identical to your Duster in every way that matters. My first set of tires were 245s.
I lost track of the number of times I spun out with those 245s back there, going around a corner and gassing it just a tiny bit too much.
I leave it to your imagination what your 440 will do.
Spun-out means broke traction and lickitty-split spun around 180*; usually putting me up on the median, with cars passing, and another broken alloy wheel. When it starts you have just micro-seconds to correct; after that you are just along for the ride, so hang on.
 
I had 245/60-15 tires on a very low powered 16 second Duster. It would chirp the tires going into second gear at the race track. Now my tires were Cooper Cobras so not the best traction tire. If you can step up to a 275/60-15 in the rear (which is easy with the right wheels) you will be glad you did! Lots of drag radials available in that size too!

Cley
 
KOZ45 said:
I goofed, the rear wheels I have are 14 x 7, not 14 x 6 as I initially posted

According to what I have found, I can run the following width on 14 x 7 wheels:

215
225
235
245
Click to expand...

Not even sure they sell tires in all these sizes, just doing some conversions online

225/55/14; 23.7 x 8.9
225/60/14; 24.6 x 8.9
225/65/14; 25.5 x 8.9

235/55/14; 24.2 x 9.3
235/60/14; 25.2 x 9.3
235/65/14; 26.0 x 9.3

245/55/14; 24.6 x 9.6
245/60/14; 25.6 x 9.6
245/65/14; 26.5 x 9.6
 
255/55/14; 25.0 x 10.0
255/60/14; 26.0 x 10.0
255/65/14; 27.1 x 10.0

265/55/14; 25.5 x 10.4
265/60/14; 26.5 x 10.4
265/65/14; 27.6 x 10.4

275/55/14; 25.9 x 10.8
275/60/14; 27.0 x 10.8
275/65/14; 28.1 10.8
 
Rear setup when I bought the car:

G50-14; 24.625 x 10"
14x8 with 3.50" backspacing
 
You must log in or register to reply here.
-

Back
Top