68 Mustang fastback 18" wheels

[cooperscobra]

I am trying to buy some new rims and tires for my 68 mustang fastback. Unfortunately, I am deployed in Iraq so measuring everything is not an option for me. Really do not know much about this at all and I am somewhat confused with what I have found, seems there is a lot of conflicting info about this on the web. The majority of what I have found online, a 4.5 backspacing is needed in the front and rear to run an 8" width. The rims I am looking at have a 4 backspacing. So I am thinking I need a half inch spacer, right? Is there any adverse effects to using spacers? Was not sure if my handling would be effected or not. Mainly because of the looks, I am considering a 18x 9.5 rim in the rear. I spoke to my local shop and they said it would not be too difficult to allow this wheel to fit. What all would need to be done? Still kind of lost on all this.

My car currently has four wheel drum brakes but I have ordered the TCI independant front suspension with 12"rotors. Any info would be very appreciated. Thank you all in advance

 

[eleanor_350]

You're thinking backwards on the backspacing. Backspacing is measured from the mounting face of the wheel to the backside of the rim. If you put a half inch spacer behind a wheel with 4 inch backspacing, you have effectively reduced the backspacing to 3.5". The greater the backspace, the further in-board the wheel is going to set.

 

[68EFIvert]

I have had two sets of 18's on the back of my car. The first was a 4.5 bs and and 8" wide. It was a little tight I would have felt more comfortable with 4.75". 255 40 fit well with those wheels. My current set is 9" wide and the extra was all to the inside so it is 5.75 bs. I am running 275 35 now. Next time I get tires I will step up to 285/35's though.

 

[68GT500KR_Vert]

I'm running the Shelby Wheels - CS67 Chrome (18x8.5 front / 18x9.5 back) & BFGoodrich g-Force™ T/A® KDW (245/35ZR18 front / back 285/35/18)

18x8.5 Backspacing: 6.4" Offset: +42
18x9.5 Backspacing: 6.82" Offset: +40

They fit perfectly, but I have front and rear coil-over suspension:

 

[4MuscleMachines]

You can correctly fit 18x8 and 18x9.5 wheels on your car without any issues. The key is to measure more than twice to see if the backspacing you are going with fits. Most cars will differ by about .25-50 inches. More so if they have been modified with aftermarket suspensions or rear ends.

In summary, you need to verify the fit yourself before ordering your wheels. Try borrowing some wheels with the backspacing you are thinking of using and mount them on your car to see if they fit right.