Wheel back spacing questions?

[jpm1221]

Hello Everyone. I have owned my 1966 Ford Mustang coupe for 24 years and finally have the opportunity to do what I have always wanted to do. I am making it a more powerful and better handling street car. I now have a 347 stroker, 4 speed toploader and Traction lock 9" rear. I am nearing the completion of my project and am trying to figure out what wheel (back spacing) will best fit in the rear. I will be using 17" x 7" Torq Thrust 2 rims up front and 17" x 8" out back.

My questions right now are centered around the rear wheel back spacing as well as tire size. I want to run as wide of a tire as I can without rubbing the inner or outer wheel well. I have a 10.5" rear disc brake conversion and 5 leaf mid eye springs to lower the rear about 1". From what I understand, a 245/45/R17 tire on a 17 x 8 rim with 4.75" bs (AR Torq Thrust 2 specs) is about as wide as you can go on the smaller 1965 and '66 wheel wells. Some people say they get rub on outer lip and others say it is fine. I have not rolled the fenders. What is the best way to determine the correct back spacing?

Here is what I have tried:

I put a straight edge on the mounting surface of the rotor pointing up towards the wheel well and an 8" long piece of wood (width of rim) on the end of the straight edge (parallel with axle) to make a "T" in the same general locations as the lips of the rim. I marked the 8" long piece of wood in inches from one end to the other. I then slid the 8" piece of wood along the straight edge towards the center of the car so the 4.75" mark was in line with the rotor mounting surface. This gave me the location of where the lips of the 8" rim will sit inside the wheel well with a 4.75" backspace. I had more available space on the inside of the wheel well than on the outside. Am I trying to have the rim centered in the wheel well? That would lead me to believe that I could use more back spacing to move the entire rim position towards the center of the car and away from the outer wheel lip giving me room for more tire.

Does this make sense and is it right?

Any suggestions?

Thank you

[jjordan]

You need to consider the first thing that will hit into the equation. An 8" wheel measures 8" BEAD SEAT to BEAD SEAT, there is material outside the bead seat that is not measured in he wheel width calculation but is for sure going to come into play in your first to rub real world. On some cast wheels this material can be significant. Try to find a similar wheel and figure the rim thickness into your equation.

[PTS]

Hello Everyone. I have owned my 1966 Ford Mustang coupe for 24 years and finally have the opportunity to do what I have always wanted to do. I am making it a more powerful and better handling street car. I now have a 347 stroker, 4 speed toploader and Traction lock 9" rear. I am nearing the completion of my project and am trying to figure out what wheel (back spacing) will best fit in the rear. I will be using 17" x 7" Torq Thrust 2 rims up front and 17" x 8" out back.

My questions right now are centered around the rear wheel back spacing as well as tire size. I want to run as wide of a tire as I can without rubbing the inner or outer wheel well. I have a 10.5" rear disc brake conversion and 5 leaf mid eye springs to lower the rear about 1". From what I understand, a 245/45/R17 tire on a 17 x 8 rim with 4.75" bs (AR Torq Thrust 2 specs) is about as wide as you can go on the smaller 1965 and '66 wheel wells. Some people say they get rub on outer lip and others say it is fine. I have not rolled the fenders. What is the best way to determine the correct back spacing?

Here is what I have tried:

I put a straight edge on the mounting surface of the rotor pointing up towards the wheel well and an 8" long piece of wood (width of rim) on the end of the straight edge (parallel with axle) to make a "T" in the same general locations as the lips of the rim. I marked the 8" long piece of wood in inches from one end to the other. I then slid the 8" piece of wood along the straight edge towards the center of the car so the 4.75" mark was in line with the rotor mounting surface. This gave me the location of where the lips of the 8" rim will sit inside the wheel well with a 4.75" backspace. I had more available space on the inside of the wheel well than on the outside. Am I trying to have the rim centered in the wheel well? That would lead me to believe that I could use more back spacing to move the entire rim position towards the center of the car and away from the outer wheel lip giving me room for more tire.

Does this make sense and is it right?

Any suggestions?

Thank you

Call me at 1-855-353-7883 and I will help you get the backspace.

Regards,

Perry
PTS

[DriverzInc]

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