need backspacing help

[MrHernandez]

ok, i'm buying a new set of rims for the cutlass, 16x8, thing is there are different backspacing options and i have no idea what to get, was hoping some of you guys could shed some light and help me make a decision http://www.wheelsforless.com/SearchResu ... s=IO62568b

 

[81elcamino]

i have 15x8 wheels with 3.5 inches of backspace and can fit a 275 60 tire on an 81 elco, idk if that helps

 

[mr evil]

I believe stock is 3.5"
I run 15x8 with 235/60 in front and 255/60 back. Only issues I have is occasional bottoming due to needing new springs in front.
I would keep the bs stock on front at least, it is where you will have issues if you're going to have them. You'll have to pay attention to tire profile/size closely as well. I had a car with 235/50/16 in front, but can't remember the bs on that wheel, but the tire wheel combo was smaller than my 235/60/15 combo.

 

[MrHernandez]

thanks for the feedback, can anybody else shed some light? :?

 

[jrm81bu]

With my old torque thrust II's, also 16x8. I ran a 4 3/4 bs. Too much for the rear, had to use a 5/16 spacer. And a 255/50/16 tire. In the front I ran 16x7 with a 4 1/2 bs and 215/60/16 tire. No problems with the front.

 

[FE3X CLONE]

On my '87 I had 17x8's with 4" BS and 255/45ZR17 tires. These fit perfectly in the wheel well. I would imagine a 16x8 with a 255/50 would be similar.

Try doing some measuring of your wheel wells to be sure before hand. Use a straight edge and put it up against your brake drum where the wheel mounts, then run a tape measure back to the frame. Then use a string and a plumb bob (metal washers, etc.) and tape it to the inside lip of your outer fender. Measure from the brake drum out to the string. This will give you the total width of your wheel well and then you can work on different backspacing and where it will put the wheel within that space.

 

[billyjack]

4" BS is probably your best bet with an 8" wheel. Anything greater will give you clearance problems on the inside, putting the tires too close to the rear frame rails in the rear, and reducing available steering lock in the front by having the tire sidewall rub the frame. Going less than 4" starts to move the wheels too far outboard, so you're looking at wheelwell lip interference. All my experience is with an El Camino. Do some searching in this forum and you'll find many comments of different tire and wheel sizes, but 4" BS still seems to be the safe bet.

Bill

 

[MrHernandez]

Thanks for the help everybody, think i'm going with 4" 😀

 

[DrRansom442]

I assume you have 14" x 6" with a 3.5" backspacing (stock) now? I can not seem to find them now but I had roughed up some graphics to explain fitting larger rims. I WILL find those and post ... but in essence you have a 6" rim, you want a 2" larger rim. Assuming your backspace for the 6" rim is 3.5" ... you want to ideally distribute the difference equally ... 1" forward/1" back a.k.a. a 4.5" offset ...now as I said this is ideally. You will need to make some measurements to make sure you have that one inch forward and that 1 inch back without rubbing. You will want to check this unsprung and with the tires stock tires on the ground. Ideally you do want to double check this on YOUR car. As age and alignment could be factors too. Always better to be safe than to be sorry. 1/4" here and there can make a world of difference (says the man that found out the hard way that early 70s A-bodies and G-bodies have a slightly different offset - after I rubbed some brand new tires a 3/8" space went in). I beleive you are going to actually come up with 4.25" offset to be right, but please do the measurements ... don't assume I am right. 4" I think you might be pushing the rear tires into the 1/4 panels.

 

[jrm81bu]

If it makes any difference, currently I'm running 17x8 with 4.5 bs and a 235/50 tire. No problems in the rear. I've also used the exact same setup with one inch spacers effectively making it 3.5 bs and again no problems.