widebody back spacing offset confusion
 

ok so i've read plenty of confusing threads regarding backspacing offsets et - and + and spacers and have seen many pictures of great looking cars and wheels that simply state the wheel sizes with no rim offsets sizes . now im super confused but i believe i moving in the right direction to acquire a set of deep dish wheels with little to no spacers for my 80 sc steel widebody car with sc trailing arms and turbo front and rear fenders.

... i am currently looking to order a set of braid 17x9/11
from what i understand 9s with a +3 and the 11s with a -21 should fit under my 80 wide body conversion ( assuming the conversion was done correctly and it does appear to be done correctly)... from what i understand from the offset chart. The +3 on the 9s and the -21 on the 11s should give me a 5 1/8" offset /backspace on the rims . giving me the option to adjust the stance a little out with up to a 1/4" spacer if needed.
so after reading a lot about offsets and backspacing and looking at offset charts and diagrams i am a little confused . according to the pictures A zero offset on a 9 inch rim splits the rim right down the middle giving a 4.5" in the front and 4.5" in the back .. but if you look at the chart a 0 offset has a 5" backspacing and 4 inch front spacing from center line .. ( what am i missing ???) there appears to be a 1/2 inch variance on all the offsets ..
i would love to hear from someone who is running 9s with an et offset between -3 and +3 and 11s between a -21 and -27 wondering about rubbing, spacers, no spacers and what tires you are using and a picture would be great ..

Thanks in advance



Regards Ned

http://forums.pelicanparts.com/porsche-911-technical-forum/679934-please-share-your-widebody-rim-tire-fender-specs-pics-drool.html

http://forums.pelicanparts.com/porsche-911-technical-forum/601556-17-wheel-build-how-wide-should-i-go.html

http://forums.pelicanparts.com/porsche-911-technical-forum/586236-need-help-tire-sizes-wide-body.html

http://forums.pelicanparts.com/porsche-911-technical-forum/679934-please-share-your-widebody-rim-tire-fender-specs-pics-drool.html

Not for the centre but from the mounting surface. The variance you are seeing may be the hub thickness of the wheel

Also, ook at tire sizes. I went with 275 rear tire and a 10.5 rear rim since an 11 is too wide for a 275 and that tire was more widely available.


Essentially take your stock rim and add all of the additional width to the front side
(You can squeak a bit more out of the backside if needed as you can see in some of the threads)

all good reads there are probably 50 other older threads all the same showing tire sizes . but none address what offsets are used and whether spacers were used . would love to hear from someone who used a 11x17 -21 to -27 et on a widebody .