I put a ford 9" in my car and am think it might be too short.

What is the safe back spacing range for a 9.5" rear wheel?

MTmace

 

I ran 7.5" on a 15X10, any less and it will start to stick out, i have pics in my sig.

 

I have a 68 with 8" Wheels right now. Those wheels have a 4.5" back spacing with a 1" spacer attached to my Axel. The wheels are 15" and have some pretty tall slicks and they do not stick out at all.

I want to go with 17" wheels that are 9.5" wide.
I am thinking since I needed the 1" spacer I would need a 3.5" back space on my wheel.

I don't think with this setup the tires will stickout that much. But with backspacing set at 3.5" will this be safe?

MTmace

 

No one can answer the question without at least knowing the year of the car. The first person who responded thought it was a 4th Gen.... the second is talking about a 1st Gen. Why not add a "signature" with the year of your car, so people can give you accurate answers without guessing.

And, without know the year of the car or the exact width of the 9-inch, I'm not sure how anyone could tell you the required backspace.

Finally.... there's a "Wheels and Tires" forum.... I'll move the post there.

 

I don't understand why the difference in year would make on the safety of the wheel back spacing. The geometry should be the same and pressure on the outer rims should be relatively the same no matter what car their on.

MTmace

 

The backspace determines where the wheel/tire sits under the fender. If the backspace is incorrect, the wheel/tire will be outside the fender or up against the inner fender liner.

The wheel manufacturer will take the backspace of the wheel into consideration when he designs the wheel. The wheel will have a specific load rating, and may place further restrictions on applicatio - e.g. "not for street use", "not for drag racing", "not for road course". That will determine whether the wheel is structurally sound for your car.

If AFS designs sells you a 17x11 7.93" backspace wheel, for a 4th Gen F-Body, you can assume that the wheel will be structually sound in that application. If Weld designs and sells you a 5x10" 7.5" backspace drag wheel for the same application, you can assume that the wheel will stand up to that application.

But only by knowing the year of the car to get an idea of where the fenders are, and the width of the axle to know where the hub flange can you select the correct backspace for a wheel.

If you are after some other sort of info, or want to get into the theory on how a wheel is designed, finite analysis, etc..... I can't help you. Maybe someone else can.