17" backspacing measurements / Advice

K

kwissman

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Joined Jan 5, 2000

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208 Posts

Discussion starter · #1 · Jan 21, 2001

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Well I spent all afternoon measuring my car for new wheels. I have templates of 245/45-17 and 275/40-17 tires mounted on wheels that I used to measure for the backspacing. I came up with with 5' backspacing with a 17x8 for the front. It may require a small shim around 1/4" to keep the tire from rubbing the frame. The rear was 5.5 with a 17x9.5. I am not sure if the 275s will fit on the rear. It was really close on the front inner side at around 9 to 10 o'clock. My car is lowered 2" in front and rear. I don't want to have to do any fender well trimming in the rear, since I paid 1000 for an OEM quarter last winter. Any advice would be appreciated.

Kent Wissman
67 SS 427

 

T

Teetoe_Jones

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Joined Oct 11, 2000

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612 Posts

#2 · Jan 21, 2001

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You may want to check that again. I have 17x8 with 4-1/2" of backspacing on all 4. Fronts are 235/45/17, and rears are 275/40/17. No clearence issues. With a 17x9 i'd go with 5" of backspacing, but a 17x8 in front should only need 4-1/2, and you may want a smaller tire.
Tyler

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1968 RS/SS Camaro w/ 94 vette LT-1 and T56 six speed, Cal-Tracs, Baer 12" crossdrilled brakes 17" rims, ect....
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My 68 with LT1 and T56</A>

 

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RockyMtnRacer

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Joined Jul 26, 1999

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755 Posts

#3 · Jan 21, 2001

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I'm running a 245/45/17 tire up front on 17x7" wheels with a 4" BS. So, if you go to 8" wheels then 5" sounds about right. I have 255/45/17's out back on a 17x8 wheel with 4" BS but I have a 9" rear that's a little different width from a stock Chevy rear.

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Scott
'69 400SB, Richmond 5-speed
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M

MarkM

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Joined Dec 6, 1999

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1,515 Posts

#4 · Jan 21, 2001

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Kwissman, those measurements sound pretty good to me. Do you have the measurement from about 13" up from the wheel mounting surface to the inner fender? A 275/40 17 has a diameter of about 25.6" tall, so I used 13 as about half. A 275/40 has a Ovarall width of about 11", so if you have 5.5" of backspacing and you take the 9.5" wheel and a 11" section you should add about .75" to the 5.5" backspacing to equall 6.25", so if you know how much room you have from the mounting surface to the inner fender it would tell me if you have the correct backspacign, hope that made sence. Let us know what you finally get and how they work out for you.

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68 468 700R4, and here it is;
mutert23

 

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John Doyle

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Joined Sep 4, 2000

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729 Posts

#5 · Jan 22, 2001

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I'll bet you rub up front and will have to trim out back. On my '67, I'm running 17 x 7's w/ 4.5" b.s up front with 235/45's and a 2" drop. The look is great but I still get a rub on a hard bump. Out back are 4.75" b.s. 8's with 255/50's with no trimming & no problems there.

John