What backspace will make a 17x8 look like a 17x9

[gray68]

I have found several rims i am interested in for my 68 camaro that only come in a 17x8 or a 17x10. Since a 17x10 won't fit I figure with the right back space I could get the same visible depth of 9" or 9.5" wheel. I will be running a 245 up front and a 255 on the rear. Any recommendations for backspace front and rear?

[gearbanger]

Depends on what backspace the 17x9 has.

[astroracer]

If you set the 17 x 9 in the center of the available space you would need 1" less back spacing on a 17 x 8 to put the face of the wheel at the same spot as the 17 x 9. Ex: a 4 1/2" back spacing on a 17 x 9 would need to be 3 1/2" on a 17 x 8. This doesn't mean you should order a 3 1/2" BS... You need to measure your car (on both sides) to see what your available space is and calculate from there.
I would suggest leaving the wheel centered. This way you can go to a larger tire (like a 275) and not contact the outer wheel well lip.
Mark

[gray68]

would it be 1" difference? I know the backspace for a 17x8 upfront would be 4.5", and a 17x9.5 on the rear would be 5.5. So even if I took off an inch that would be a 4.5" backspace on the rear with a 17x8. which would be the same as the front. That doesn't seem right??? by my figures on a 17x8 wheel I would need to go to a 3" backspace to achieve the same depth as the 17x 9.5 wheel, which works out to a 2.5" difference between an 8" and a 9.5" wheel, is my math incorrect?

[gray68]

would it be 1" difference? I know the backspace for a 17x8 upfront would be 4.5", and a 17x9.5 on the rear would be 5.5. So even if I took off an inch that would be a 4.5" backspace on the rear with a 17x8. which would be the same as the front. That doesn't seem right??? by my figures on a 17x8 wheel I would need to go to a 3" backspace to achieve the same depth as the 17x 9.5 wheel, which works out to a 2.5" difference between an 8" and a 9.5" wheel, is my math incorrect?

ooops! my math is wrong! it should be a 4" backspace for a 1.5 " difference

[MBD]

would it be 1" difference? I know the backspace for a 17x8 upfront would be 4.5", and a 17x9.5 on the rear would be 5.5. So even if I took off an inch that would be a 4.5" backspace on the rear with a 17x8. which would be the same as the front. That doesn't seem right??? by my figures on a 17x8 wheel I would need to go to a 3" backspace to achieve the same depth as the 17x 9.5 wheel, which works out to a 2.5" difference between an 8" and a 9.5" wheel, is my math incorrect?

Look at it another way. If you have a 9.5 inch wheel with 5.5 inches of backspacing you have 4 inches outboard of the mounting surface (5.5 BS + 4.0 outboard = 9.5).

If you want that same 4 inch dish on an 8 inch wheel, that you have with the 9.5 inch wheel, you need 4 inches of backspacing (4.0 BS + 4.0 outboard = 8.0).

Standing beside the car looking down at the wheel, you would not be able to tell the difference between the dish on the 8s and 9.5s. It is only when you squat down behind the car that you would notice the 8s are narrower.

To answer your original question, if your front 8 inch wheels have 4.5 inches of backspacing, and you want the rears to have the 4 inches of backspacing discussed above, the difference in backspacing front to rear is .5 inches per side.

[Andrew McBride]

view my photobucket link for pics.

I have 17x9.5 w/5.5.' BS

you can fit that size in the rear w/out any problem. Also 17x8 w/ 4.5" works well in the front.

[gray68]

Thanks for the input. i wanted to go with a 9" or 9.5" but the wheels I am planning on getting are only offered in a 17x8 or a 17x10 (which is too big) I don't understand why but most of the wheel manufacturers do not make a 17x9 in a soft lip???

[boosttoy]

Dont forget to add a inch to the advertised wheel width 1/2 inch per side for the lip.Example if you have a 9.5 inch wheel the widest point is 10.5 inches,with a 5.5 inch backspacing you will have 5 inches from the
mounting pad to the outer lip.This info can be found at www.americanracing.com in the tech center section,
Later, Frank