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My wheels are 8 inches with 4 inches of backspace. All you gain is .7 inches? I though you were suppose to get 9.5 to 10 inches of wheel. But when I was looking at it the spring looks like that is not possible.
I just purchased an 11" wheel with 315 width tires for this setup. The BS is only part of the width. Can go wider, but fender well, etc are considerations as well.
I do not want to increase the wheel to the outside only on the inside. That is why I want to add to the back space. Confused on how much back space you can run and what does it hit first with offset arms. The arms or spring?
I'm running 5.25" backspacing with a bit of tire bulge. The closest points of contact are the frame (2 o'clock on the driver's side) and the end of the composite spring. Your wheel diameter and ride height will determine if your spring becomes a limiting factor or not.
Diameter of the wheel plays a part too. Larger diameter wheels and the spring end may fit inside the wheel, otherwise you need to buy a shortened spring or shorten yours (I shortened mine). Rear sway bar is also a consideration. Offset arms are not even required for larger diameter wheels if you are able to do the work to relocate the handbrake cable. On my car, i relocated the handbrake cable on top of the standard arms, shortened the main leaf in the rear spring, and rebent the swaybar to sit closer to the chassis rail. My road wheels are 17x9.5 with a 5.05" backspace and a 285/40R17, my track wheels are 18x10 with 5.54" effective backspace (5.74" with a 0.200" spacer) and 295/30R18, both sets fit fine with no discernible rub front or rear except on the front chassis rail/swaybar when near full lock.
I'm running 15x9 wheels with an effective backspace of 5 inches. P275/60/15s with global west offset control arms.
I had to shorten my composite spring 1inch on each side. Also had to move the parking brake cable mount to the top of each control arm.
Set my body height with the 10 inch bolts. They needed to be cut off so they wouldn't hit the inside edge of the wheel.
That's a lot of mods because of the wheel diameter. My advice is go bigger diameter wheels and tires for numerous reasons. This would give you the option of putting bigger brakes on if desired as well as better quality tire availability.
I have 9.5" wheels with 285/40/18 tires on the back. You can go with 5 or 5.5" BS without hitting anything. Dont forget what works for one Vette might not work with another one
Diameter of the wheel plays a part too. Larger diameter wheels and the spring end may fit inside the wheel, otherwise you need to buy a shortened spring or shorten yours (I shortened mine). Rear sway bar is also a consideration. Offset arms are not even required for larger diameter wheels if you are able to do the work to relocate the handbrake cable. On my car, i relocated the handbrake cable on top of the standard arms, shortened the main leaf in the rear spring, and rebent the swaybar to sit closer to the chassis rail. My road wheels are 17x9.5 with a 5.05" backspace and a 285/40R17, my track wheels are 18x10 with 5.54" effective backspace (5.74" with a 0.200" spacer) and 295/30R18, both sets fit fine with no discernible rub front or rear except on the front chassis rail/swaybar when near full lock.
5.54" backspacing works in the front on your car? Any mods to the control arm/tie rod/etc. to make that work?
5.54" backspacing works in the front on your car? Any mods to the control arm/tie rod/etc. to make that work?
Works fine, no mods required. They do reduce available steering lock (due to rubbing on frame/swaybar as mentioned), but as they are my track wheels and tyres that's not a problem to me, you only ever notice in tight parking maneuvers. Would not fit if they were 17"s (at least on my car), as my 17"s with 5.05" backspace are very close to the tierod end, I could not go any wider at all. But with the 18"s the tierod fits inside the wheel and there's no problems at all. Having said that... I've bought but not yet fitted some VB&P bump steer blocks, which may possibly cause an issue with the 18"s and the tie rod ends (but I expect will provide more clearance for the 17"s). I think they'll be ok, but will have to fit them to be sure. I have Global West upper arms, but I don't believe they make any difference to wheel fitment. Honestly, big wheels and tyres seem to fit more easily on the front than the rear. I guess most people just prefer a staggered look?
Last edited by Metalhead140; 01-03-2018 at 11:31 PM.
Thanks for all of the replies. I have Global West arms on the way but it looked like I would have more problems with other parts running wider rims. Looks like 9.5 would be the best for 17 inch wheels not reworking everything else. Dennis
Thanks for all of the replies. I have Global West arms on the way but it looked like I would have more problems with other parts running wider rims. Looks like 9.5 would be the best for 17 inch wheels not reworking everything else. Dennis
Or for better rubber options "18" wheels.
I have 18x9.5" with 4.75" All around using 275.40R18 wheel. No mods to the factory suspension anywhere including rear sway bar.
Last edited by cagotzmann; 01-04-2018 at 07:45 PM.
I did a very careful study and took notes on sizes listed on the sticky' "Show your aftermarket wheels". My conclusion was that 18x10 with a 5.25" backspace would fit. That couldn't have been further from the truth. I then carefully cut off the parking brake bracket to relocate to the top and still issues. I had to replace the rear suspension with a Sharkbite suspension and Van Steel offset trailing arms. The trailing arms had to be modified with special brackets from Speed Direct which required professional welding. Following installation of the new offset trailing arms and the Sharkbite suspension which was a huge job, the rear sway bar just slightly touches the edge of each tire at the mid-point. I am planning on taking the rear sway bar to a machine shop to have it bent slightly; (about 3/8" on each side) which should provide clearance for the tires. As previously stated, each car is slightly different. My project developed into something more than I expected...but am very happy with the result
I am afraid that will happen to me. Changing one part leads to another. The way the car is setting now with 15" wheels there is only 3/4" clearance from the spring. Hope using 17" wheels will make it a little better. But I will not buy any wheels until I have the new global west parts installed. Hopefully I can measure and see what I need. I have been thinking about buying the 3 piece wheels so if I get the urge for wide wheels I can add flairs and outside rim halves.
...the rear sway bar just slightly touches the edge of each tire at the mid-point. I am planning on taking the rear sway bar to a machine shop to have it bent slightly; (about 3/8" on each side) which should provide clearance for the tires. As previously stated, each car is slightly different. My project developed into something more than I expected...but am very happy with the result
Unfortunately that's the truth, nothing beats measuring your own car - though I'm surprised your wheels wouldn't fit with a shortened spring? If it's a factory sway bar, it can be bent without too much difficulty by securing it in a vise and hanging a piece of pipe off the end for leverage - that's how I did mine. I bent it a bit further at the rear 90 bend to tuck it closer to the chassis rail, then bent it out again at the bend that drops it down towards the trailing arm, as that sits inside the wheel/tyre area (at least on a 17"+ wheel).
Unfortunately that's the truth, nothing beats measuring your own car - though I'm surprised your wheels wouldn't fit with a shortened spring? If it's a factory sway bar, it can be bent without too much difficulty by securing it in a vise and hanging a piece of pipe off the end for leverage - that's how I did mine. I bent it a bit further at the rear 90 bend to tuck it closer to the chassis rail, then bent it out again at the bend that drops it down towards the trailing arm, as that sits inside the wheel/tyre area (at least on a 17"+ wheel).
My prior '69 with stock fenders had 18x9 4.75 BS wheels and that was the absolute max that would work with stock control arms, VBP shortened spring and sway bar. It was TIGHT! 5.25 B.S. works on my current car with Van Steel offset arms, VBP shortened spring and no sway bar.
01-03-2018, 10:00 AM
