Good Backspacing for new rims

[DartVadar]

So I've finally made up my mind about the rims I want to buy for my 73 dart swinger with the stock 7.25 rear (I'm building an A-body 8.75 to drop in soon).

I want to order some billet specialties street lites! 15x6 with 3.5 backspacing up front and 15x8 with either 3.5, 4.5 or 5.5 backspacing.

What would be a good backspacing for the rear? I'm planning on using 235-245 tires on the rear, and 215s on the front maximum. As I understand 235 are about the widest a stock rear wheel well can accommodate without modifications.

Also how important is the center bore diameter on the hub and the rims? I assume its recommended to use hub centric rims?

 

[Beatnik]

You'll want to go with 4.5" backspacing. Assuming the rear is going to stay stock? You can get. 255/60 in there. Up front a 215 tire is gonna be pretty tall. I've had them on my Duster and they rubbed at times. A 205/70 even 205/65 would be a better choice.

 

[DartVadar]

Thanks, Yeah for now the rear is going to stay stock. I'll look at some tires with 4.5 backspacing, and maybe go a bit smaller up front.

 

[DartVadar]

You'll want to go with 4.5" backspacing. Assuming the rear is going to stay stock? You can get. 255/60 in there. Up front a 215 tire is gonna be pretty tall. I've had them on my Duster and they rubbed at times. A 205/70 even 205/65 would be a better choice.

To fit a 255 tire in the rear is that with 8 inch or 7 inch wide rims with 4.5" backspacing? It would be nice to fit that wide of tire in the rear.

I know for most rims I can only find an 8 inch wide rim with 4.5" backspacing, and a 7 inch wide rims with 3.75" backspacing.

 

[Jo Diesel]

My car has 15x8 with 4" back space and I fit 235/60/15 in the front and 255/60/15 in the rear. Had 275/60/15 on it but they rub slightly on spring and handled like crap!

 

[DartVadar]

My car has 15x8 with 4" back space and I fit 235/60/15 in the front and 255/60/15 in the rear. Had 275/60/15 on it but they rub slightly on spring and handled like crap!

Is that with the smaller dart wheels wells? and if so that what I want to run. But what rims have 4 inch backspacing? I'm only seeing 4.5" for most 15x8 rims.

 

[petnic01]

I'm running 275/60/15 in the back on 15 X 7 American Racing Outlaw rims with 4" backspacing with no issues. I'm actually considering going to a taller and wider tire

 

[Woods74]

Remember tire selection for 15" sucks.

 

[72bluNblu]

To fit a 255 tire in the rear is that with 8 inch or 7 inch wide rims with 4.5" backspacing? It would be nice to fit that wide of tire in the rear.

I know for most rims I can only find an 8 inch wide rim with 4.5" backspacing, and a 7 inch wide rims with 3.75" backspacing.

A 15x8 with 4.5" of backspace should fit, and you should be able to get a 255/60/15 on there too, even on a Dart. That should be just about perfect with an 8 3/4. With the 7 1/4 it will be tight on the springs, the 7 1/4 A body rears are actually a little narrower than the 8 3/4's. But worst case, if you did need a spacer they'd be a 1/4" or less. No biggie.

I'm running 275/60/15 in the back on 15 X 7 American Racing Outlaw rims with 4" backspacing with no issues. I'm actually considering going to a taller and wider tire

Looks like that's on a Duster though, and that's a whole different ballgame. 275's won't fit on a Dart without one of the 1/2" spring offsets. I know, I've tried. On my '71 Dart my 275/40/17's actually just touched the springs and the quarters. I got the wheel in there, but there's no way it would work on the road without a spring/hanger offset and some quarter lip trimming.

On a stock Duster 275's work great. But to go bigger, you really need to consider a 1/2" spring offset and/or trimming the quarter lip. Unless of course your car sits up high in the back and the wheels can hang out of the quarters without rubbing. I have 295/35/18's on my Duster, but I also have a 1/2" spring relocation, cut a good 1/2" off of the quarter lip, and have pretty much zero extra room anywhere. Doesn't rub, but its about as tight as you can make it.

 

[DartVadar]

A 15x8 with 4.5" of backspace should fit, and you should be able to get a 255/60/15 on there too, even on a Dart. That should be just about perfect with an 8 3/4. With the 7 1/4 it will be tight on the springs, the 7 1/4 A body rears are actually a little narrower than the 8 3/4's. But worst case, if you did need a spacer they'd be a 1/4" or less. No biggie.



Looks like that's on a Duster though, and that's a whole different ballgame. 275's won't fit on a Dart without one of the 1/2" spring offsets. I know, I've tried. On my '71 Dart my 275/40/17's actually just touched the springs and the quarters. I got the wheel in there, but there's no way it would work on the road without a spring/hanger offset and some quarter lip trimming.

On a stock Duster 275's work great. But to go bigger, you really need to consider a 1/2" spring offset and/or trimming the quarter lip. Unless of course your car sits up high in the back and the wheels can hang out of the quarters without rubbing. I have 295/35/18's on my Duster, but I also have a 1/2" spring relocation, cut a good 1/2" off of the quarter lip, and have pretty much zero extra room anywhere. Doesn't rub, but its about as tight as you can make it.

I was just given an 8 3/4 rear end, the spring perches have been moved in a 1/2 inch and the entire rear end has been shortened slightly. I know I can probably go a tad wider than 255s but I don't know how wide I want to go.

I ordered 15x8 w/4.5 backspacing and 15x6 w/3.5 backspacing billet specialties street lites, once I get them I'll order tires that I want. Should look good! I haven't seen as many cars running those rims.