Maximum rim backspacing for narrow bodied car, Seeking opinions and measurements Options

[toadman]

I am looking at a set of used rims for my stock, narrow bodied 1976 914. These rims are not local to me. The rims would be fitted with 205/50/15 Hoosier race tires and used for drivers ed events.

I currently have the tires on stock 5.5X15 4-bolt Fuchs alloys. I was concerned about possible tire rubbing on the front shock dust covers so I removed them. I have used this tire/rim setup for two drivers ed events and had no problems. The backspacing on my Fuchs rims is 4.65 in.

The rims I am considering are 7X15 and have the stock 4-bolt pattern. However, these rims have a 5.5 in. backspacing.

First question - does anyone here have one of the older ATS 7X15, 4-bolt rims that can measure the backspacing for me?

Second question(s) - is anyone here running 205/50/15 tires on ATS 7X15 4-bolt rims, or other 7 in. wide rims, on a narrow bodied car? If yes, did you have to pull the rear fenders or make other modifications? Were there any problems with tires rubbing the body or fenders or suspension parts at the front or rear?

Third question - do you think 205/50/15 Hoosier race tires on 7X15 rims with 5.5 in. backspacing will fit a narrow bodied car without any problems? Stated another way, if the tire stays the same, will going to a wider rim affect the width of the tire once it is mounted and on the ground?

Thanks, everyone

[r_towle]

Put on your ole rims and measure the space on the rear between the tire and the body at about 2 o'clock as you look at the wheel.
That is where they rub on the rear.

Put them on the front , turn the wheel lock to lock.
Look at the body at the rear, about 4 o'clock, bottom edge of the fender well, that is where they rub.

You can get speakers at pepboys in 3/8 inch thickness.

[stugray]

With those same tires and fuchs, my rears would rub on the inside fender wells.
So I used 3/8" spacers which required racing studs.
Fronts were fine with the shock protector tubes removed.

I then purchased 15X7 steelies that had been widened by welding in the ring.
They work fine with different spacers, but I havent documented all of my dimensions on paper yet.

[toadman]

With those same tires and fuchs, my rears would rub on the inside fender wells.
So I used 3/8" spacers which required racing studs.
Fronts were fine with the shock protector tubes removed.

I then purchased 15X7 steelies that had been widened by welding in the ring.
They work fine with different spacers, but I havent documented all of my dimensions on paper yet.

Thanks for the info. I would be more comfortable not using spacers.

What is the backspacing on your 15X7 steelies?

Did you have to pull the rear fenders when using your 15X7 steelies and spacers?

[r_towle]

Back spacing and offset are two different things.

Back spacing will help you figure out rubbing on the inner fenders.
Offset will help you figure out both inner and outer rubbing.

And remember, what fits on my car will NOT fit on yours.
All the back ends seem to be different and most are different from one side to the other, so you need to figure it out on your specific car.

Put any set of wheels on there and get underneath the back to measure clearance.
From there, you can do the math for any wheel.

[mskala]

When you start pushing the limit of what fits, there are differences
front to rear and side to side because of the way the cars are built and
the possible alignment differences.

Do not be afraid of the basic spacers. I have an assortment of 1/16",
1/8", 1/4" because with race tires it can be be super tight fit. You can't
really even static measure it, as the tires move on the rims. Try to leave
at least 1/4" space from tire to anything. Rear can be moved up and down
after removing the strut.