Need help with wheel size and back spacing? - Team Camaro Tech
Wheels & Tires What fits what?

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post #1 of 6 (permalink) Old Dec 25th, 06, 10:22 PM Thread Starter
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Question Need help with wheel size and back spacing?

I have searched through several past posts and there is alot of conflicting info regarding backspacing for 17" and 18" wheels on a 1969 Camaro. I would like to use either 17" or 18" but need to know for sure what sizes and backspacing will fit. From what I can gather I think I can use a 17x8 with 4.75 backspacing using a 235/45/17 tire in the front and a 17x9.5 with 5.5 backspacing using a 275/40/17 tire in the rear, is this correct? There was not to much info on using an 18" wheel so if you could prvide info for what sizes and backspacing is correct I would appreciate it? I am planning in the future to lower the car 2" in the front and 1.5" in the rear with the Hotchkis TVS kit, so if that makes a difference in the backspacing I would need to know that also. Also if you could show pictures of your car with 17" or 18" and list the size, backspacing and if it is lowered that would be great. Thanks for the help
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post #2 of 6 (permalink) Old Dec 26th, 06, 07:37 AM
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Re: Need help with wheel size and back spacing?

Those backspaces don't sound bad, but... follow the old saying "measure twice cut once" in this case "measure twice on all four corners, buy wheels once." don't believe what you read figure it out yourself and use what everyone tells you as guidance only. These old cars can vary a lot on some of these measurements.

A 275/35/18 tire has the same overall width and diameter of a 275/40/17 so which ever you decide on should not effect your backspacing.

You can use tireracks site to look up width and diameter of different tires. There can be some variation between manufacturers.

Good luck.

1968 that started life and a 6 banger with a PG. Now it's a 350 with a TKO600, Moser 12 bolt, Speedtech LCA/UCA, ATS Tall Spindles, Hotchkis Springs, Forgeline ZX3P, C5 (Kore3) brakes with other cool stuff from Ron Davis, Vintage Air and soon to be Terminator EFI.

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post #3 of 6 (permalink) Old Dec 26th, 06, 03:46 PM
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Re: Need help with wheel size and back spacing?

I can hopefully shed a little light on this subject very soon. I like you want the same thing. I'm waiting on my Hotchkis kit so I can install it and measure once again. I too plan on using the 17's same size and BP as you just described. I'm looking for that slightly tucked look. I hope it all works out.
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post #4 of 6 (permalink) Old Dec 26th, 06, 05:40 PM
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Re: Need help with wheel size and back spacing?

The reason why we all tell you to proceed with caution is because these cars are lmost 40 years old and who knows what they have been through. Some of the things that can cause clearence problems are both sides not equal to start with (production tolerences were not as tight then as they are now), replacement panels with repro parts or not installed perfect, sagged or rotted bushings, disc brake kits pushing the wheels out, and not all tire sizes are created equal. As far as 17s or 18s go the backspacing doesn't change because the side wall aspect ratio goes down and overall tire height stays near the same. The 8" front wheels use 4.75" backspace and the rear 9.5" wheels use 5.5" backspace. You will find some cars have deviated slightly from that usually no more than an additional .25" backspace. You will also see that some cars have dropped down to a 255 rear tire because the owner did not want to tolerate any rubbing or the car ride height is very low (3" drop or more). You will also see that 2" or 3" dropped springs will not yeild the same results on all cars. That should really confuse you now. The point is not all cars measure exactly the same and the answers we give you are proven to work in almost all cases. Thats why you will also see posts where people have fit 10" wide wheels with 285 tires in the rear. In most cases they have rolled or trimmed the wheel lips and beaten the inner wheelwell in. I think that's why this question gets beat to death. Everone sees what has worked but when you're spending the kind of money you are for wheels/tires you want to be sure. That's why we say to measure every car. The best situation is to test fit someone else's or something close to get an idea.


Last edited by JV69z/28rs; Dec 26th, 06 at 05:43 PM. Reason: spelling
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post #5 of 6 (permalink) Old Dec 26th, 06, 10:00 PM Thread Starter
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Re: Need help with wheel size and back spacing?

What backspacing would be used for a 17x7 or 18x7 front and a 17x8 or 18x8 rear wheel and what size tires? Thanks
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post #6 of 6 (permalink) Old Dec 27th, 06, 10:10 AM
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Re: Need help with wheel size and back spacing?

FRONT: 17x7 - 4.25" Backspace - 225/45R17
FRONT: 17x8 - 4.75" Backspace - 235/45R17
REAR : 17x8 - 4.75" Backspace - 255/45R17
REAR : 17x9.5 - 5.5" Backspace - 275/40R17

18" - Same Backspace

I run 17x8 235/45R17 and 17x9.5 275/40R17 on my Camaro, lowered 1" Front (Eibach) and 1.5" Rear (Hotchkis)
See my Signature Line below for a link to all the picture of my 69 Camaro. No rubbing, I do have the rear quarter lips rolled for best clearance though

1969 Camaro - GM 2003 Electron Blue
Beck Racing 383 cu in 465HP Engine - Sean Murphy Inductions Stage 2 Quadrajet
TCI Streetfighter 350 - 3.73:1 Posi 10 Bolt Rear - 12.6 sec qtr mile

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