backspacing info please

[Anonymous]

I am going to be running polished centerline autodrags. The car is an 81 GMC caballero Diablo. fronts are 15" x 3.5" and the rear rims are 15" x 8.5".
I already have the front tires and am planning on running bf goodrich radial T/A's 275 60r 15's.....on an 8" rim i need 3.5" BS...what am I going to need for the 8.5" rim....I really do not want to make a mistake when I order them....thanks alot for the replies.

 

[Tony_SS]

you should be ok with 4" of b.s.

 

[Anonymous]

my steel rallies are 15x8 and actually measure out at 8.5. I have a 4 1/4 backspace and could easily do 4 1/2. 5 would be do-able,just looks like it would be real close.

 

[Tony_SS]

the 8" measurement is on the inside of the lip. it'll measure 8.5 on the outsides.

i had 4" bs on 15x8 255/60/15s on my 84 elco. i wouldnt go more than 4.5". id go with 4" to be safe.

 

[Anonymous]

that is where it was measured at.the 15x6's were dead on

 

[Anonymous]

also,they are aftermarket wheels,which could account for the inaccuracy in the listing

 

[Supe]

My 15x8 with 4.5 BS and a slick would not clear without a notch or a spacer. 4" would be ideal, as you would have plenty of room both ways, but would also have the option of going to a larger tire later on if necessary.

 

[Hiway]

I put an 4.5 bs Draglite with a 275/60 and 8.5"s wide on my ole man's elcy and it needed a 3/8" spacer to clear the frame. Stock rear and sits a little low due to worn springs. Just my .02 8) 4" would work well.

 

[GreenDragginBu]

got 4" on my telstars and it is the most i could go without a notch....no rubbing.

but with the autodrags 15 x 8.5 or the 15 x 7 only come in a 3 5/16 b.s. or a 4 7/8 b.s. and the 4 7/8 b.s i tried before with a 275/60 and it wouldnt work without a notch or spacer.

 

[BigMone]

What will the spacing or offset be in metric form in millimeters?