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Discussion Starter · #1 ·
Okay, for the "umpteenth" time (but not from me)... I have decided to go with 17" wheels for my '55 sedan, so what is the best offset for the front wheels? I am building a nice street car - big block, manual trans, disc brakes all around, F*RD 9-inch. I'm wanting to set up the suspension before moving up, so I need to get my wheels set up. I was thinking 17x7 with either 4.5 or 5 inch backspace? Unless anyone here can suggest otherwise? I figured a 225/45-17?

On the rear I was going to go with about 17x9.5 with a 274/45 or maybe 285/40? Leaf springs will be pocketed and trunk will be mini-tubbed. I'd go with wider rims on the rear, but cannot find good radial street tires to go on them.

Thanks!
 

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On the front, 7" rims with a 5" backspace may rub on the inside.
 

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size rims

I have heidt's narrowed upper and lower control arm coil over QA1 with 2 inch dropped spindel with 12 inch brake, looks like twin piston caliper fm camaro fm ebay seller mgchevy. relocated springs and doing 2 or 3 inch mini tub currently.

reason for changing brakes because bearings frozen and threads on spindle ruined. the kit was installed in 1996 by a friend using chevelle calipers with 10 1/2 rotors so that i could install 14 inch cragars.

I bought a 15 inch ss cragars with 3.37 backspace because 4.1 would rub the rotors. will wait for income tax money to upgrade.

If i remember correctly eckler's classic chevy has an article that if you relocate and do a mini tub you can get a 17x9.5 with 6 1/2 backspacing without any problem. I have looked and the biggest 17 inch tie you can get is 285. The width is less than 12 inches needed for clearance. I was looking more towards 295x9.5x18 by 45. will post pictures of mini tub.
 

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The best backspacing to use on a 7" wide rim on the front is 4.5". You aren't going to be able to get 5" backspacing on most wheels anyway, whether it would clear on the inside or not. In fact, 4.5" backspacing is special order on most "off the shelf" wheels like TT2s. The usual backspacing for "off the shelf wheels is 4.00". Of course you can get a billet wheel made in just about any backspacing up to the design limit. With most of the billet wheels that limit is 4.500" backspacing.

The above recommendation is for a spindle/brake package that moves the wheel mounting surface out between 0 and 3/8". The usual disc brake conversion on a stock spindle moves the wheel out much further than this.

On the back, you have a lot more latitude, and more variables that will work. You need to use Chevynut's wheel/tire calculator to match everything up.
 

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Discussion Starter · #5 ·
This place is the best!

Thank you guys for your input! I don't know of any other boards that would get this many great responses, especially this fast!

I've been eyeballing the COY'S C57 wheel and they are 7" with 4.25 backspace. Should be just right, right? (Has anyone heard anything about COY'S I should be concerned about?) I'm not too woried about the rear wheel sizes because I'm going to go with a shortened 9-inch.

Are 18's overkill??? COY'S S57 only comes in18" (or more) with a 9.5 width. Can't get a 17x9.5. If I do 18 in the back should I do 18x7 up front, or stick with 17x7 there? I can't seem to make up my mind until I actually buy the item! And then I think twice about whether I bought the right thing! My wife tells me I'm a "mess"!!! (I think she says it lovingly, though.)

Thanks guys!
 

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rims size

I will use chevy nut calculator once the mini tub is done to be sure proper rim fitting on rear. You are correct about 17 x 7 or 17 x 8 with 4.5 backspacing for the front. Still have not figure out how to post picture. I am getting close? Please take a look at my garage for picture. Thanks...
 

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By swapping to a No Limit Trailing Arm suspension and narrowed 9", I am able to squeeze my 17'' American Racing rims with 13" wide tires under there. I will have to tub and will have about an inch on either side of the rubber for clearance...it can be done. Tojach
 

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17X7 with 4.25" BS works, 4.5" would be better but it's not available from Coy. With 4.25" BS you may want to run a 215 instead of the 225 tire.
Why not run the 20X10 out back with 18X7 up front?

One thing about Coy's being made in China they are well priced but the chrome lasts about 2 years. I have used four or five sets.
 
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