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I'm researching new wheels and tires and need input from those that have done this already. I am interested in a 285/40-18 tire, and want to keep my rear sway bar, so the question I need answered is the backspace. Right now I run 295/55-15 drag radials on 15x9 wheels with an effective 4.25 inch backset. The tires have been on for six years, never rub anywhere, but do stick out past the fender approximately one inch.
New wheels will allow me to try and correct this.....maybe. I am confident that 18x 9.5 with a 4.5 inch backset will fit almost exactly like what I now run,...with the sway bar in place. I can order custom backset wheels, just need to know how far I can go and still keep the sway bar.
Option B,...loose the bar, and try putting the tire under the fender completely. Those that have done this,...do you really notice the lack of rear bar?
And on the front,...has anybody tried 18x9.5 with 4.75 backset wheels...Should be the same wheel centerline as stock, but allow maybe a 275/40 tire.
I forgot to mention, I have offset T-arms and a VB&P 360 lb rear spring already, and no fender flairs. My sway bar is a VB&P 3/4 inch that bolts on with little tabs to the offset T-am, similar to what Richard454 mentioned. It is not the stock bar.
I have looked through the archives, and a lot of you guys have gone to 18 x 9.5 wheels, but nobody mentions running a rear sway bar.
Also it would be great if you have pics showing the fender lip to tire, so I can get an idea of what offset might work for me. I realize all our cars are a little different, but if ten guys come up with the same wheel, and it works.....I'm guessing it would work for me.
This is the 295/55-15 as of now. As you can see the tire just pokes out past the fender about an inch. Otherwise......perfect.
Last edited by The Money Pit; Apr 11, 2017 at 10:08 AM.
From: Graceland in a Not Correctly Restored Stingray
Although your car's balance will necessarily move in the direction of understeer from wherever it is now if you remove the rear bar, this can be offset by increasing rear spring rate - something that would also serve to reduce squat. Good on you for inquiring, as all too many who are focused on straight-line performance overlook this not so small detail.
ill check tire size when I get home but i know when i bought spaces for my Zo6 replicas i was shooting for 5" bs. stock trailing arms ans sway bar on my 79.
I have 18 x 9.5 with 285/40/18 tires on the rear with a 5.25 back spacing. I also have offset trailing arms. The stock sway bar does not fit. I had to buy a narrow bar.
Just to give you an idea what I have now.....In my opinion, it isn't all that bad. But I figure for what the new wheels cost......I could at least try to improve the fit.
If you already have offset trailing arms then the moving the handbrake I discussed with you isn't an issue. 18x9.5 with a 4.5" backspace will sit half an inch further out than the pics of my car I sent you, which are fairly flush with the guards. I think if you want a flush fit to the arch then you need the 5" backspace on a 9.5" wheel. A 4.5" backspace will look basically the same as what you have now in terms of how much it sticks out from the arch. You may or may not need a shortened spring and/or aftermarket or re-bent swaybar with the 5" backspace - I think the spring would probably fit within the wheel on an 18", and not be an issue. I had no trouble modifying my swaybar to fit with my 5" backspace wheels - I just clamped it in a vice and used a large piece of pipe over the end to bend it. I bent it at the original bends. I pulled the 90 degree bend in tighter, to tuck the bar closer to the chassis, then at the dogleg bend I bent it back out again (as this sits inside the wheel). It wasn't difficult, required no specialised tools, and worked very effectively, I've had no rub on the tyres or chassis whatsoever.
18 x 9.5 inch wheels offset question
